阅读说明：本技术 控制双向幅材张力的设备和使用该设备控制双向幅材张力的方法 (Apparatus for controlling tension of bi-directional web and method for controlling tension of bi-directional web using the same ) 是由 李承炫 权信 金广泳 曺正大 金贤昌 于 2019-07-16 设计创作，主要内容包括：控制双向幅材张力的设备和方法,所述设备包括：张力调节装置,包括相对于沿幅材宽度方向的旋转轴线旋转的张力调节辊和设置在张力调节辊旋转轴线的两侧末端处的一对张力调节辊连接器；设置在所述一对张力调节辊连接器的每一个处且沿着幅材宽度方向彼此间隔开的一对张力调节装置移动部件,包括抑制根据张力调节辊因幅材张力改变而沿张力控制方向移动而生成的力的阻尼器移动部件和平行于阻尼器移动部件设置且沿着张力控制方向移动的主动移动部件；测量部件,测量幅材张力；边缘检测传感器,检测幅材两个末端的位置；控制器,控制张力调节装置移动部件因幅材张力改变而沿张力控制方向的移动位移,且独立控制所述一对张力调节装置移动部件的移动位移。(Apparatus and method for controlling bi-directional web tension, the apparatus comprising: a dancer device including a dancer roller that rotates with respect to a rotation axis in a web width direction and a pair of dancer roller connectors provided at both side ends of the rotation axis of the dancer roller; a pair of dancer moving members provided at each of the pair of dancer roll connectors and spaced apart from each other in a web width direction, including a damper moving member that suppresses a force generated according to the dancer roll moving in a tension control direction due to a web tension change, and an active moving member that is provided in parallel with the damper moving member and moves in the tension control direction; a measuring component that measures web tension; edge detection sensors that detect the position of both ends of the web; and a controller for controlling the movement displacement of the tension adjusting device moving components along the tension control direction due to the change of the web tension, and independently controlling the movement displacement of the pair of tension adjusting device moving components.)

1. An apparatus for controlling bi-directional web tension, the apparatus controlling web tension and comprising:

a dancer device including a dancer roller that rotates with respect to a rotation axis extending in a web width direction, and a pair of dancer roller connectors provided at both side ends of the rotation axis of the dancer roller;

a pair of dancer moving members including a damper moving member provided at each of the pair of dancer roller connectors and spaced apart from each other in the web width direction, and an active moving member provided in parallel with the damper moving member and moving in a tension control direction that suppresses a force generated according to the dancer roller moving in a tension control direction due to a change in the web tension, the tension control direction being perpendicular to the web width direction and a web conveyance direction;

a measuring component that measures the web tension;

edge detection sensors that detect positions of both ends of the web in the web width direction; and

a controller that controls a movement displacement of the tension-adjusting-device moving member in the tension-control direction due to a change in the web tension, and independently controls the movement displacement of the pair of tension-adjusting-device moving members.

2. The apparatus of claim 1, wherein the controller controls the tensioning device moving component based on the positions of the two ends of the web received from the edge detection sensors.

3. The apparatus of claim 1, wherein the controller calculates reference tensions T1 and T2 applied to the pair of dancer moving members, respectively, based on the web tension T, web width, and the positions of the two ends of the web received from the edge detection sensors,

wherein the controller controls the movement displacement of the pair of tensioning device moving members based on the calculated reference tensions T1 and T2.

4. The apparatus of claim 1, wherein the response speed of the actively moving component ranges between a mechanical time constant of 0.01 seconds and 0.001 seconds.

5. The apparatus of claim 1, wherein the damper moving component applies a force that compensates for web tension changes,

wherein the active moving component performs dynamic suppression of disturbances to uniformly maintain the web tension.

6. The device of claim 1, wherein the active moving part is a linear drive device selected from at least one of a voice coil motor, a linear motor, a solenoid, and a piezoelectric actuator.

7. The apparatus of claim 1, further comprising:

a large-range moving member that moves more actively in the tension control direction than a movable range of the active moving member, the large-range moving member being provided in parallel with the active moving member and in series with the damper moving member to actively suppress a force generated according to the dancer roll moving in the tension control direction due to a change in the web tension,

wherein a movable range of the large-range moving member is ten to hundred times larger than a movable range of the active moving member.

8. The apparatus of claim 7, wherein the large-range moving member is a linear driving apparatus selected from at least one of a servo motor, a pneumatic cylinder, and a hydraulic cylinder.

9. The apparatus of claim 1, wherein the measurement component further comprises:

a pair of load cells that measure a force generated according to the dancer roll moving in the tension control direction due to a change in the web tension, and the pair of load cells are provided at each of the pair of dancer roll connectors.

10. The apparatus of claim 1, wherein the measurement component further comprises:

two pairs of load cells that measure the force generated as the dancer roll moves in the tension control direction due to changes in the web tension, and the two pairs of load cells are disposed at each of the pair of dancer roll connectors such that the load cells are disposed between the dancer roll connectors and the damper moving member and between the dancer roll connectors and the active moving member.

11. The apparatus of any of claims 9-10, wherein the controller independently feedback controls the displacement of each of the pair of tensioning device moving members based on the force measured in the load cell.

12. A method of controlling bi-directional web tension using the apparatus of claim 1, the method comprising:

determining a reference tension of the web while conveying the web;

moving the dancer roll in the tension control direction due to the change in the web tension when the web tension deviates from the reference tension;

passively suppressing, by the damper moving member, a force generated according to movement of the dancer roll in the tension control direction; and is

The pair of active moving members at both side ends in the web width direction are independently controlled to actively move the pair of active moving members in the tension control direction to perform dynamic suppression against disturbance.

13. The method of claim 12, wherein determining the reference tension of the web comprises:

obtaining a web tension applied to the dancer roll;

detecting, by the edge detection sensors, the positions of both ends of the web; and

calculating the reference tensions T1 and T2 applied to the pair of dancer moving members, respectively, based on the tension of the web and the positions of both ends of the web.

14. A method of controlling bi-directional web tension using the apparatus of claim 7, the method comprising:

determining a reference tension of the web while conveying the web;

moving the dancer roll in the tension control direction due to the change in the web tension when the web tension deviates from the reference tension;

passively suppressing, by the damper moving member, a force generated according to movement of the dancer roll in the tension control direction;

controlling the pair of large-range moving members at both side ends in the web width direction to actively move the pair of large-range moving members in the tension control direction and to move the pair of large-range moving members by the same movement displacement so that the tension of the web approaches within the interference range of the reference tension of the web; and

the pair of active moving members at both side ends in the web width direction are independently controlled to be effectively moved in the tension control direction to perform dynamic suppression against disturbance.

15. The method of claim 14, wherein determining a reference tension of the web comprises:

obtaining the web tension fully applied to the dancer roll;

detecting, by the edge detection sensors, the positions of both ends of the web; and

calculating the reference tensions T1 and T2 applied to the pair of dancer moving members, respectively, based on the tension of the web and the positions of both ends of the web.

Technical Field

The present disclosure relates to an apparatus for controlling bidirectional web tension and a method for controlling bidirectional web tension using the same in a web transfer apparatus included in a roller printer that performs printing or transfer on a web (e.g., a flexible substrate), and more particularly, to an apparatus for independently controlling bidirectional web tension and a method for independently controlling bidirectional web tension using the same, which can more accurately and precisely control web tension of a roller and more uniformly control bidirectional web tension.

Background

Recently, in manufacturing electrical apparatuses, the following printing is widely used: wherein the conductive ink is printed directly to form an integrated circuit. At the time of printing, an electrical printing process can be performed in a flexible substrate having a film type, and thus a flexible electrical device can be manufactured, thereby making it possible to use printing more widely.

Printing to print a predetermined pattern on a web, such as a flexible substrate, is also used for conventional printing. However, the electrical printing process in which highly integrated circuits are formed requires a more precise and accurate printing process than conventional printing. Thus, roller printers for use in an electrographic printing process should be more accurately and precisely controlled in, for example, the position of the web than conventional roller printers.

Conventionally, a roll printer comprises an unwinder unwinding the web to be patterned and a winder rewinding the web on which the pattern is formed, and further comprises a feeder arranged between the unwinder and the winder for transferring the web from the unwinder to the winder. The feeder rotates uniformly to transfer the web from the unwinder to the winder uniformly. The printing process is performed between the unwinder and the feeder, and thus a printing device that directly prints a pattern, a drying device that dries printed ink, and the like are provided between the unwinder and the feeder.

With long use of the printing device, the motor rotating the roller may not be uniformly maintained, or the web may relax or shrink due to temperature. Therefore, the release speed of the unwinder, the winding speed of the winder, or the conveying speed of the feeder may vary, so that the tension of the web may not be uniformly maintained. Here, in order to compensate for tension changes of the web, a tension adjusting device (dancer) is included in the printing apparatus for reducing tension variations of the web.

Fig. 1 is a schematic view showing the operation of a tension adjusting device, and as shown in fig. 1, the tension adjusting device is disposed between an unwinder and a winder, and properly pushes a web using self-load force, pneumatic force, or the like. As in the state of fig. 1, when the tension of the web is uniformly maintained, the position of the tension adjusting means is also stably maintained. However, when the tension of the web increases rapidly, the tension adjusting device rises, and when the tension of the web decreases rapidly, the tension adjusting device falls. Therefore, when the position of the tension adjusting device is changed up and down, the tension change of the web is reduced due to the position change of the tension adjusting device, and thus the printing error of the printing device disposed after the tension adjusting device can be reduced. Korean patent laid-open No. 10-2016-.

The web is twisted in the width direction so that the tension of the web can be changed in the width direction. In the conventional roll printing, errors due to the above-described reasons may be negligible, but in the electrical printing process, accuracy in the μm range is required, and thus errors due to the above-described reasons may degrade the quality of products. In addition, the tension adjusting device as shown in fig. 1 may not compensate for tension changes due to twisting of the web in the width direction of the web, which is perpendicular to the conveying direction of the web.

Conventionally, a serpentine control device is provided in a web conveyor to uniformly maintain the tension of the web at both side ends. In the serpentine control apparatus, a pair of rollers having a cylindrical shape extending in the web width direction are disposed at a predetermined distance in the web conveyance direction, and the pair of rollers are moved left and right in the web width direction to compensate for the twist in the web width direction, so that the inclination of the web is lowered. Japanese patent publication No. 2009-269745 ("serpentine control system and serpentine control method") discloses the above-described technology. However, the serpentine control apparatus corrects only the skew due to the twist of the position of the web even if the tension change in the web width direction is due to various causes (except for the twist of the web position). Therefore, additional techniques for controlling tension changes along the width of the web should be developed.

Disclosure of Invention

The present invention has been developed to solve the above-mentioned problems in the related art. The present invention provides an apparatus for controlling the tension of a bi-directional web that is capable of more accurately and precisely controlling the web tension of a roll and more uniformly controlling the bi-directional web tension.

In addition, the present invention also provides a method of controlling bi-directional web tension using an apparatus for controlling bi-directional web tension.

According to an exemplary embodiment, an apparatus for controlling bidirectional web tension controls web tension and includes a tension adjustment device, a pair of tension adjustment device moving parts, a measuring part, an edge detection sensor, and a controller. The dancer device includes a dancer roll and a pair of dancer roll connectors. The dancer roll rotates relative to a rotational axis extending in the width direction of the web. A pair of dancer roll connectors are provided at both side ends of the rotation axis of the dancer roll. The pair of dancer moving members includes a damper moving member and an active moving member, and the pair of dancer moving members are provided at each of the pair of dancer roller connectors and spaced apart from each other in the web width direction. The damper moving member suppresses a force generated according to the movement of the dancer roll in the tension control direction due to a change in web tension. The tension control direction is perpendicular to the web width direction and the web transport direction. The active moving member is disposed parallel to the damper moving member and moves in the tension control direction. The measuring means measure the web tension. The edge detection sensors detect the positions of both ends of the web in the web width direction. The controller controls the movement displacement of the tension adjusting device moving members in the tension control direction due to the change in the web tension, and independently controls the movement displacement of the pair of tension adjusting device moving members.

In an example, the controller may control the tensioning device moving member based on the positions of both ends of the web received from the edge detection sensors.

In an example, the controller may calculate reference tensions T1 and T2 respectively applied to the pair of tensioning device moving members based on the web tension T, the web width, and the positions of both ends of the web received from the edge detection sensors. The controller may control the movement displacement of the pair of tensioning device moving members based on the calculated reference tensions T1 and T2.

In an example, the response speed of the actively moving component can range between a mechanical time constant of 0.01 seconds and 0.001 seconds.

In an example, the damper moving member may apply a force that compensates for web tension changes. The active moving part may perform dynamic suppression for disturbances to uniformly maintain web tension.

In an example, the active moving part may be a linear driving device selected from at least one of a voice coil motor, a linear motor, a solenoid, and a piezoelectric actuator.

In an example, the apparatus may further comprise a large range of moving parts. The large-range moving member moves more actively in the tension control direction than the movable range of the active moving member, is disposed parallel to the active moving member, and is disposed in series with the damper moving member so as to actively suppress a force generated according to the dancer roll moving in the tension control direction due to a change in web tension. The movable range of the large-range moving member is ten to one hundred times larger than that of the active moving member.

In an example, the wide range moving part may be a linear driving apparatus selected from at least one of a servo motor, a pneumatic cylinder, and a hydraulic cylinder.

In an example, the measuring means may further comprise a pair of load cells measuring a force generated according to the dancer roll moving in the tension control direction due to a change in web tension, and provided at each of the pair of dancer roll connectors.

In an example, the measuring means may further comprise two pairs of load cells measuring forces generated as the dancer roll moves in the tension control direction due to web tension changes, and disposed at each of the pair of dancer roll connectors such that the load cells are disposed between the dancer roll connectors and the damper moving means and between the dancer roll connectors and the active moving means.

In an example, the controller may independently feedback control the displacement of each of the pair of tensioning device moving members based on the force measured in the load cell.

According to another exemplary embodiment, in a method for controlling the tension of a bi-directional web using the apparatus, a reference tension of the web is determined while the web is being conveyed. When the web tension deviates from the reference tension, the dancer roll moves in the tension control direction due to the web tension change. The force generated according to the movement of the dancer roll in the tension control direction is passively suppressed by the damper moving member. The pair of active moving members at both side ends in the web width direction are independently controlled to actively move the pair of active moving members in the tension control direction, thereby performing dynamic suppression against disturbance.

In an example, the web tension applied to the dancer roll may be obtained when determining a reference tension for the web. The position of both ends of the web may be detected based on edge detection sensors. Reference tensions T1 and T2 respectively applied to the pair of tensioning device moving members may be calculated based on the tension of the web and the positions of both ends of the web.

According to yet another exemplary embodiment, in a method of controlling bi-directional web tension using the apparatus, a reference tension of the web is determined while the web is being conveyed. When the web tension deviates from the reference tension, the dancer roll moves in the tension control direction due to the web tension change. The force generated according to the movement of the dancer roll in the tension control direction is passively suppressed due to the damper moving member. The pair of large-range moving members at both side ends in the web width direction are controlled to actively move the pair of large-range moving members in the tension control direction, and move the same movement displacement so that the tension of the web approaches within the disturbance range of the reference tension of the web. The pair of active moving members at both side ends in the web width direction are independently controlled to actively move the pair of active moving members in the tension control direction, thereby performing dynamic suppression against disturbance.

In an example, the web tension applied to the dancer roll may be obtained when determining a reference tension for the web. The position of both ends of the web may be detected based on edge detection sensors. Reference tensions T1 and T2 respectively applied to the pair of tensioning device moving members may be calculated based on the tension of the web and the positions of both ends of the web.

According to the present exemplary embodiment, in the web conveying apparatus, the tension of the web rolling in the roller can be controlled more accurately. The position of the active tensioning device for controlling the tension of the web is actively controlled, and a Voice Coil Motor (VCM) having a relatively faster response rate and capable of more accurately and precisely controlling the position is used to control the position of the active tensioning device. Accordingly, a roll printer for an electrical printing process requiring accuracy in the μm range can be controlled to have a required accuracy.

In addition, the tension in the left-right direction along the width direction of the web can be independently controlled, and therefore the tension of the web in the left-right direction can be more uniformly maintained. In the conventional art, for example, controlling the rotational speed of a winder or an unwinder to control the tension of a web, or controlling the tension of a web using only a tension adjusting device, the tension in the left-right direction of the web may not be uniformly maintained. In the conventional art, for example, with a serpentine control apparatus, when the tension is changed due to inclination, the tension in the left-right direction of the web may be uniformly controlled, but when the tension is changed due to various reasons other than inclination, the tension thereof may not be uniformly controlled. In contrast, in the exemplary embodiment of the present invention, the tension of the web is precisely controlled and the tension of the web in the left-right direction is independently controlled, and thus the tension of the web is completely controlled and uniformly maintained, compared to the above-described conventional art.

In addition, the apparatus and method of the exemplary embodiment of the present invention are applied to roll printing used in an electrical printing process, and thus products having high precision can be manufactured faster, thereby improving manufacturing efficiency of electrical apparatuses and reducing a fraction defective more.

Drawings

FIG. 1 is a schematic view showing the operation of a tension adjusting device;

FIG. 2 is a schematic diagram showing a web transport apparatus having an apparatus for controlling bi-directional web tension according to an exemplary embodiment of the present invention;

fig. 3A and 3B are a perspective view and a front view showing the apparatus of fig. 2;

FIG. 4 is a side view showing the moving parts of the tension adjusting means in the apparatus of FIG. 2;

FIG. 5 is a graph showing the results of web tension control in the moving part of the tensioning device of FIG. 4;

FIG. 6 is a side view showing tension adjustment device moving parts in an apparatus for controlling bi-directional web tension according to another exemplary embodiment of the present invention;

FIG. 7 is a graph showing the results of web tension control in the moving part of the tensioning device of FIG. 6;

FIG. 8 is a side view showing an apparatus for controlling bi-directional web tension according to yet another exemplary embodiment of the present invention;

FIG. 9 is a front view for explaining a method of controlling bi-directional web tension using the apparatus of FIG. 8; and is

Fig. 10 is a flow chart showing the method of fig. 9.

Reference numerals

100: apparatus for controlling tension of bidirectional web

110: tension adjusting device 111: tension adjusting roller

112: dancer roller connector 113: guide roller

114: the guide roller coupler 120: tension adjusting device moving part

121: damper moving member 122: active moving part

123: the large-range moving member 130: measuring element

131: the guide roller load cell 132: tension adjusting roller force cell

133: moving member load cell 150: controller

160: edge detection sensor 500: web material

Detailed Description

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity.

It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure.

Spatially relative terms (such as "inner," "outer," "below," "lower," "above," "upper," and the like) may be used herein for ease of description to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the term "lower" can encompass both an orientation of upper and lower. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.

Fig. 2 is a schematic diagram showing a web transport apparatus having an apparatus for controlling bi-directional web tension according to an exemplary embodiment of the present invention. Fig. 3A and 3B are a perspective view and a front view showing the apparatus of fig. 2.

Referring to fig. 2, an apparatus for controlling bidirectional web tension 100 (hereinafter, "tension control apparatus") is provided at any position in a web conveying apparatus including an unwinder, a feeder, and a winder. For example, when the web conveying apparatus is a roller printer for electrical printing, the printing apparatus may be provided at a central portion of the web conveying apparatus, and the tension control apparatus may be provided at a front side of the printing apparatus.

Additionally, as shown in fig. 2, the tension control apparatus 100 may be very similar to the tension adjustment device as shown in fig. 1. Conventionally, the tensioning devices push the web with a constant force via self-loading or pneumatic force and thus the tensioning devices move perpendicular to the transport direction of the web. In addition, the tension adjusting device moves passively according to the tension change of the web, and thus active control may not be possible. In contrast, in the present exemplary embodiment, the tension control apparatus 100 actively controls the force applied to the web, and thus the tension of the web can be actively controlled. In addition, as shown in fig. 3A and 3B, the movement of the tension control apparatus 100 in the left and right directions is independently controlled, and thus the tension of the web can be easily compensated for in the following cases: in the case of a web that is twisted, or in the case of a rotating speed of the left and right sides of the web, its surface shape, its axial alignment, and its tension non-uniformity.

Referring again to fig. 3, the tension control apparatus 100 controls the tension of the web 500 conveyed in the web conveyance direction, and includes a tension adjusting device 110, a tension adjusting device moving part 120, a measuring part 130, and a controller 150.

The dancer 110 includes a dancer roller 111 and a pair of dancer roller connectors 112. The dancer roll rotates relative to the axis of rotation and has a cylindrical shape. Here, the rotation axis extends in the web width direction. A pair of dancer roller connectors 112 are provided at both side ends of the dancer roller 111, and rotatably connected to the central axis of the dancer roller 111 to support the dancer roller 111. The tension adjusting means 110 may further comprise at least one guide roller 113. The guide roller 113 rotates with respect to a rotation axis extending in the web width direction and has a cylindrical shape. The guide roll 113 guides the web 500 to be rolled on the dancer roll 111. In fig. 2, two guide rollers 113 are shown for comparison with the web conveying apparatus without guide rollers, but the number and positions of the guide rollers may not be limited thereto when the guide rollers 113 change the conveying direction of the web to roll the web 500 on the dancer roller 111.

A single dancer moving member 120 is provided at each dancer roller connector 112. A pair of dancer moving members 120 are provided at the pair of dancer roll connectors 112, respectively, as shown in fig. 3A and 3B, and a pair of dancer moving members 120 are provided at each end of the web in the web width direction.

The tension adjusting means moving part 120 includes a damper moving part 121 and an active moving part 122. The damper moving part 121 and the active moving part 122 are arranged in parallel as in fig. 3A.

For convenience of explanation, the tension control direction in the dancer roller 111 is defined as a direction substantially perpendicular to the web width direction and the web conveyance direction. Here, as shown in fig. 3B, the angle of the web in the web transfer apparatus may be variously changed according to the position of the roller. Thus, the web width direction means the axial direction of the roll and is substantially the same in all rolls. The web transport direction may be changed depending on the angle of the web with which the roll is brought into contact. The web transport direction may be a tangential direction at a central portion of an arc formed by the web coming into contact with the roller. Here, the tension control direction is a normal direction at the center portion of the circular arc.

The damper moving part 121 may be a suppression shape that suppresses a force generated according to the movement of the dancer roller 111 in the tension control direction due to a change in the tension of the web 500, and may be, for example, an air damper or an air cushion. In the drawing, the damper moving part 121 is shown as a block shape, and the damper moving part 121 is shown to be in contact with the dancer roller connector 112, but is not limited thereto. For example, when the damper moving part 121 is an air damper, the air damper may be spaced apart from the object to be dampened, and thus the dancer roll connector 112 and the damper moving part 121 may be spaced apart from each other.

When only the damper moving part 121 is disposed, the tension adjusting means 110 may operate like a passively operated tension adjusting means. For example, when the tension of the web 500 is rapidly increased (when the web 500 is rapidly pulled), the dancer roller 111 that pushes the web 500 is pushed to the opposite direction (-) of the tension control direction in fig. 3. When an urging force in the opposite direction of the tension control is applied to the damper moving part 121 formed as an air damper, a repulsive force is generated. The repulsive force pushes the tension-adjusting roller 111 to the positive direction (+) of the tension-controlling direction. Thus, the pushing action of the web 500 is reduced to restore the tension of the web 500. However, since the damper moving part 121 has the damper shape, the response speed is relatively low, and thus rapid control is impossible. In addition, the control in the case where the dancer roller 111 is moved in the positive direction (+) of the tension control direction is difficult to perform. Therefore, in the present exemplary embodiment, the damper moving part 121 and the active moving part 122 are disposed in parallel to solve the above-mentioned problem.

The active moving part 122 is disposed in parallel to the damper moving part 121 to actively move in the tension control direction. The response speed of the active moving part 122 may be faster than that of the damper moving part 121, and thus interference due to high frequency, which is difficult to compensate for by the damper moving part 122, may be accurately compensated via the faster response. For example, the response speed of the actively moving component 122 may be between a mechanical time constant of 0.01 seconds and 0.001 seconds. For example, the active moving part 122 may be a linear driving device selected from at least one of a voice coil motor, a linear motor, a solenoid, and a piezoelectric actuator.

The measurement component 130 measures the tension of the web 500 and may be a load cell. The measurement member 130 may be disposed at various positions, and thus the measurement member 130 is illustrated as a block shape without specifying a position, as shown in fig. 3A and 3B. The measurement part 130 can be explained in detail with reference to fig. 8.

The controller 150 controls the movement displacement of the tension-adjusting-device moving member 120 in the tension control direction according to the tension change of the web 500. As explained above, the damper moving part 121 is not an active driving means and is passively operated due to an external force, and thus the controller 150 finally controls the active moving part 122. Therefore, in the tension control apparatus 100, the damper moving part 121 applies a force that compensates for a change in the tension of the web 500, and the active moving part 122 dynamically suppresses the disturbance, and thus the tension of the web 500 is uniformly maintained. In addition, the controller 150 may independently control the movement displacement of the pair of tensioning device moving members 120. When the tension of the web 500 is not uniform in the web width direction, which is the left-right direction in fig. 3B, the movement displacements of the tension adjusting device moving member 120 on the left side and on the right side are controlled to be different from each other, and thus the non-uniform tension of the web 500 in the web width direction can be accurately compensated.

Hereinafter, the tension adjusting device moving member 120 is explained in detail with reference to fig. 4 and 5, and as explained above, the specific structure or position of the measuring member 130 is not as shown in fig. 3A and 3B, and the measuring member 130 is shown as a block shape.

Fig. 4 is a side view showing a moving part of the tension adjusting means in the apparatus of fig. 2.

Referring to fig. 4, as explained above, the tension control apparatus 100 includes the tension adjusting device 110, the tension adjusting device moving member 120, the measuring member 130, and the controller 150, and the tension adjusting device moving member 120 includes the damper moving member 121 and the active moving member 122. In fig. 4, the web 500 is moving vertically, and the tension control direction is the left-right direction shown as an arrow in fig. 4.

Fig. 5 is a graph showing the result of web tension control in the tension adjusting device moving member of fig. 4.

In operating the web conveying apparatus, a system for maintaining the speed and tension having a predetermined range is provided in the web conveying apparatus, and thus the tension of the web can be uniformly maintained within the predetermined range. However, as indicated by the line T in fig. 5, the tension changes within a very small range like a disturbance. The system in conventional web transport apparatus may not be able to control tension variations or disturbances. However, the displacement of such disturbances is relatively very small, but may reduce the quality of the printing in exactly the same printing process as an electrical printing process requiring a high printing quality with the μm range. Accordingly, in the present exemplary embodiment, the active moving part 122 may be a voice coil motor having a fast response speed, and thus disturbances having a small displacement and a high frequency may be effectively compensated. Here, ideally, the tension of the line T shown in fig. 5 is compensated to the tension of the line T' shown in fig. 5, and thus the tension may be uniformly maintained.

The active moving part 122, such as a voice coil motor, has a fast response speed, and thus tension changes like disturbances can be compensated for, but the movable range and force are relatively small. Therefore, in the present exemplary embodiment, the damper moving member 121 is disposed parallel to the active moving member 122, and thus the displacement of the tension adjusting device in a relatively larger range due to the change in the tension of the web is reduced by the damper moving member 121, and the displacement thereof in a relatively smaller range is actively compensated by the active moving member 122.

However, the damper moving part 121 is passively operated, and thus, when the system is operated, a displacement in a relatively larger range should be generated for compensation. Therefore, the tension control apparatus 100 further includes a large-range moving member 123, which is an exemplary embodiment as in fig. 6. The large-range moving member 123 is actively controlled and can move in a range larger than that of the active moving member 122, so that the force generated according to the movement of the dancer roller 111 in the tension control direction due to the change in the tension of the web 500 can be more actively suppressed.

Fig. 6 is a side view showing tension adjustment device moving parts in an apparatus for controlling tension of a bi-directional web according to another exemplary embodiment of the present invention.

Referring to fig. 6, the large-range moving member 123 may be actively moved in the tension control direction beyond the movable range of the active moving member 122, and the large-range moving member 123 is disposed parallel to the active moving member 122 and in series with the damper moving member 121. The movable range of the large-range moving member 123 may be about 10 times to about 100 times larger than the movable range of the active moving member 122. For example, the large-range moving member 123 is a linear driving device selected from at least one of a servo motor, a pneumatic cylinder, and a hydraulic cylinder. The large-range moving member 123 has a larger movable range and a larger force than the active moving member 122 even if the response speed of the large-range moving member 123 is slower than that of the active moving member 122, and therefore the large-range moving member 123 is displaced in a larger range like the damper moving member 121, and the large-range moving member 123 is actively compensated in a different manner than the damper moving member 121.

Fig. 7 is a graph showing the result of web tension control in the tension adjusting device moving member of fig. 6.

Referring to fig. 7, the tension change of the web is shown as lines T having a disturbance and having a sinusoidal wave shape. Here, the relatively larger range is within the movable range of the large-range moving member 123, and thus the large-range moving member 123 can be easily compensated. In addition, the range of the relatively more pins is within the movable range of the active moving member 122, and thus the active moving member 122 can be easily compensated. Therefore, ideally, the tension change of the web as shown by line T is compensated by the large-range moving member 123 and the active moving member 122, and thus the tension of the web is uniformly maintained as shown by line T' in fig. 7.

As explained above, the controller 150 detects a tension change of the web, and actively controls the movement displacement of the active moving member 122 or the large-range moving member 123 based on the detection, and thus the tension of the web is uniformly maintained. As an example method for detecting tension changes by the controller 150, the force generated by web tension is measured using load cells disposed at predetermined locations. Here, the position of the load cell may be rotated differently, and fig. 8 shows an example position of the load cell.

FIG. 8 is a side view illustrating an apparatus for controlling bi-directional web tension according to yet another exemplary embodiment of the present invention. Fig. 9 is a front view for explaining a method of controlling the tension of a bidirectional web using the apparatus of fig. 8. Fig. 10 is a flow chart showing the method of fig. 9.

The tension controlling apparatus of the present exemplary embodiment according to fig. 8 is substantially the same as the tension controlling apparatus according to the previous exemplary embodiment except for the measuring part 130, and thus the same reference numerals are used for the same elements and any repetitive explanation will be omitted.

Referring to fig. 8, the measuring part 130 may be one of first to third load cells 131, 132 and 133.

For example, the measurement part 130 is implemented as a first measurement sensor 131. Here, the second load cell 132 and the third load cell 133 may be omitted. As in the tensioning-device moving part 120, the tension measuring direction is perpendicular to the web width direction in the guide roll 113 and parallel to the extending direction of the guide roll coupler 114. The tension control direction may be substantially the same as or slightly different from the tension measuring direction depending on the disposition of the tension adjusting device 111 and the guide roll 113 or the extending direction of the guide roll connector 114. Ideally, the dancing roll 111 and the guide roll 113 adjacent to the dancing roll 111 are spaced from each other along the tension control direction, and then the web passes through the dancing roll 111 and the guide roll 113, or the guide roll 113 and the dancing roll 111 in sequence, so that the web transport direction changes by 180 degrees and the tension control direction and the tension measurement direction coincide with each other. However, the tension control direction and the tension measurement direction may be slightly different from each other due to a limited space for elements, and the like. However, in order to improve the measurement efficiency, the dancer roller 111 and the guide roller 113 are arranged such that the transport direction of the web changes almost about 180 degrees, wherein the web passes the dancer roller 111 and the guide roller 113, or the guide roller 113 and the dancer roller 111 in sequence. In fig. 8, as an ideal case, both the tension control direction and the tension measurement direction are along the left-right direction, and thus coincide with each other.

In fig. 8, one guide roller 113 is disposed at the rear side of the dancer roller 111, but one guide roller 112 may be disposed at the front side of the dancer roller 111, or as shown in fig. 3, two guide rollers 113 may be disposed at the front and rear sides of the dancer roller 111. When handling at least two guide rollers 113, the first load cell 131 may handle one of the guide rollers 113.

The first load cell 131 measures the force generated from the guide roll 113 moving in the tension measuring direction due to the tension change of the web 500. In addition, a pair of first load cells 131 are provided at the pair of guide roller connectors 114, respectively, and are spaced apart from each other in the web width direction. Therefore, the first load cell 131 independently measures the change in the tension of the web 500 in the left-right direction along the web width direction. The tension changes of the web 500 are communicated to the controller 150 and thus used to feedback control the active moving part 122 or the large-scale moving part 123. The controller 150 independently and feedback controls the displacement of each of the pair of tensioning device moving members 120 using the force measured at each of the plurality of pairs of first load cells 131.

Alternatively, the measurement component 130 of the tension control device may be a second load cell 132. Here, the first load cell 131 and the third load cell 133 may be omitted. Here, the second load cell 132 measures a force generated according to the movement of the dancer roll 111 in the tension control direction due to a change in tension of the web 500, and is provided at each of the pair of dancer roll connectors 112. The controller 150 independently and feedback controls the displacement of each of the pair of tensioning device moving members 120 using the force measured by the pair of second load cells 132.

When the measuring part 130 is the first load cell 131, the dancer 110 and the tension moving part 120 are separated from each other in the measuring part 130, and the angle of the web 500 rolling in the dancer roll 111 and the guide roll 113 is changed within a relatively small range even if the dancer roll 110 moves forward or backward in the tension control direction. However, when the measuring means is the second load cell 132, the angle of the web 500 rolled in the dancer roller 111 may change by a relatively greater extent due to the number or disposition of guide rollers 113 as the dancer 110 moves forward or backward. The tension applied to the web 500 is substantially parallel to the web conveyance direction and is generated in the up-down direction along the web conveyance direction with respect to the position where the web 500 rolls at the dancer roller 111. Here, when the angle of the web 500 rolling at the dancer roller 111 is changed, the sum of the elements of the tension control direction may be changed even though the tension applied to the web 500 is not changed, and thus an error may be included.

For example, as in fig. 6, the movement displacement is too large to be controlled by the active moving member 122, and thus active control using a wide range of moving members 123 is necessary, and errors may affect control when a change in tension is detected by the second load cell 132. However, as in FIG. 5, the displacement is small enough to be controlled by the active displacement component 122, and errors may not affect control even if the tension change is measured by the second load cell 132. In addition, the second load cell 132 forming the measurement component 130 is only an internal element added to the base structure, and thus the device can be easily and inexpensively equipped and manufactured compared to a device in which the first load cell 131 forms the measurement component 130. Thus, the second load cell 132 is adapted to measure the component 130 when the displacement is relatively small.

Alternatively, the measurement part 130 of the tension control device may be formed as the third load cell 133, and here, the first and second load cells 131 and 132 may be omitted. The third load cell 133 is similar to the second load cell 132 and measures the force generated from the dancer roll 111 moving in the tension control direction due to changes in the tension of the web 500. However, the third load cell 133 is disposed between the dancing roller connector 112 and the damper moving member 121, and between the dancing roller connector 112 and the third load cell 133, unlike the third load cell 132 disposed at the dancing device moving member 112. Two third load cells 133 are provided at the single dancer roll connector 112, and thus a pair of third load cells 133 are provided at each of the pair of dancer roll connectors 112. Here, the controller 150 uses the force measured by the two pairs of third load cells 133, and then independently and feedback-controls the movement displacement of each of the pair of tensioning device moving members 120.

Hereinafter, the third load cell 133 provided at each of the damper moving part 121 and the active moving part 122 is explained in detail. When the measuring part 130 is formed as the second load cell 132, the damper moving part 121 and the active moving part 122 are disposed in parallel and thus the force can be shared. Here, when the damper moving part 121 is formed as the air damper as mentioned above, the damper moving part 121 is not normally brought into contact with the dancing roller connector 112, and a force is not applied toward the damper moving part 122 until the dancing roller 111 moves in the negative (-) direction of the tension control direction to come into contact with the damper moving part 121. Therefore, the forces applied to the damper moving member 121 and the active moving member 122 may not be uniformly shared, and thus the pair of third load cells 133 is used to independently measure the forces applied to the damper moving member 121 and the active moving member 122, so that the measurement may be more accurate.

Hereinafter, a method for controlling the tension of the web 500 using the tension control apparatus 100 is explained.

In the method, first, a reference tension of the web 500 is determined while the web 500 is conveyed. Here, when the web transfer apparatus normally operates, the tension of the web 500 may be uniformly maintained, and thus the reference tension of the web 500 may be determined as an average of the tensions measured in the predetermined stage.

When the tension of the web 500 deviates from the reference tension while the web 500 is conveyed, the dancer roller 111 moves in the tension control direction due to the tension change of the web 500.

As explained above, the damper moving member 121 passively suppresses the force generated when the dancer roller 111 moves in the tension control direction. The damper moving part 121 compensates for a relatively larger moving displacement.

Here, when the wide range moving member 123 is included in the tension control apparatus 100 and the damper moving member 121 may not sufficiently compensate for the moving displacement, the wide range moving member 123 may further compensate for the moving displacement. The controller 150 actively controls a pair of large-range moving members 123 at both sides in the web width direction in the tension control direction, and thus the tension of the web 500 is within the disturbance of the reference tension added to the web 500. Here, each of the pair of large-range moving members 123 may move substantially the same movement displacement.

With the above compensation, the active moving member 122 connected in parallel to the damper moving member 121 starts operating. The controller 150 independently controls a pair of active moving members 122 at both sides in the web width direction to actively move in the tension control direction so that the disturbance can be dynamically suppressed.

As mentioned above, the damper moving member 121 or the large-range moving member 123 moves at a relatively larger range, and both sides of the damper moving member 121 or both sides of the large-range moving member 123 in the web direction move substantially the same as each other. Here, when the left and right tensions are slightly different from each other, the active moving member 122 independently moves along both sides in the web width direction to compensate for the moving displacement, and thus the uneven tension of the web in the web width direction can be easily compensated by the active moving member 122.

Here, the controller 150 may control the moving displacement of the active moving member 122 at the left side in the web width direction to be equal to the moving displacement at the right side in the web width direction. Alternatively, the controller 150 may control the moving displacement of the active moving members 122 at both the left and right sides in the web width direction to be equal to the average of the moving displacements of the pair of active moving members 122. Thus, with any of the control methods mentioned above, both the left and right sides in the web width direction eventually follow the same position, and thus the appropriate control method can be selected by the user.

Hereinafter, the method for determining the reference tension of the web 500 may be explained in detail with reference to fig. 9 and 10.

Generally, a web conveyed by a web conveying apparatus is conveyed along a center line of a roller equipped in the web conveying apparatus. However, the web may be generally offset from the centerline of the roll. Fig. 9 shows that the web 500 rolling in the dancer roll 111 is offset from the center line of the roll. In fig. 9, it is assumed that the center line Cw of the web 500 is deviated from the center line Cr of the dancer roll 111 toward the right by a predetermined distance δ. In addition, as shown in fig. 6 and 8, it is assumed that the web 500 rolls the dancer roller 111 by 180 °, and is then conveyed. Therefore, even if the web 500 reverses the conveyance direction and returns after rolling the dancer roller 111 180 °, the angle at which the web 500 rolls the dancer roller 111 does not change regardless of the movement of the dancer roller 111, and thus the resultant direction of the force of the tension applied to the web does not change.

When the center line Cw of the web 500 is aligned with the center line Cr of the dancer roll 111, half of the total web tension is applied to each of the load cells at both ends of the dancer roll 111. For example, if the web tension is T and the tensions measured at the two load cells are T1 and T2, respectively, then T1-T2-1/2-T.

However, as shown in fig. 9, when the center line Cw of the web 500 is not aligned with the center line Cr of the dancer roll 111, and when all tension is uniformly applied to the surface of the web 500, a torque due to the tension applied to the web 500 is added to the center line Cw of the web by the dummy. Here, tension T (═ T1+ T2) may be applied to the centerline Cw of the web, which may be offset δ from the centerline Cr of the dancer roll.

The distance between the two load cells is L and the distance from the center line Cr of the dancer roll 111 to each of the two load cells is L/2, and then, the torque balance with respect to the right and left load cells is defined as equation 1 and equation 2.

[ EQUATION 1] with respect to the right load cell

Equation 2 with respect to the left load cell

L and T in equations 1 and 2 are already known or may be known by measurement. The distance between the two load cells is a known value and the tension T of the web 500 may be a predetermined reference tension or may be an average of the tensions of the web measured in predetermined stages.

Thus, equations 1 and 2 may be expressed by functions f1(δ) and f2(δ), which are functions of the distance δ between the centerline Cr of the dancer roll and the web 500 as a function of f1(δ) and f2(δ). For example, the distance δ may be measured by the edge detection sensor 160. The edge detection sensors 160 may be sensors that measure the positions of both ends of the web 500 in the web width direction, and may be, for example, ultrasonic sensors or infrared sensors.

Therefore, when the web 500 is deviated δ from the center line Cr of the dancer roll 111 and conveyed at the reference tension T, the tensions T1 and T2 calculated by equations 1 and 2, respectively, are typically applied to the two load cells of the dancer roll 111, respectively. Thus, the controller 150 determines the tensions T1 and T2 as reference tensions for the left and right sensors, respectively, and then independently controls the tension of the web by comparing the tension of the web measured by the load cells with the reference tensions.

The above-mentioned control method is explained in detail with reference to fig. 10. Referring to fig. 10, the controller 150 obtains the tension T of the web 500 (step S10). The tension T may be the tension of the web 500 fully applied to the dancer roll 111. For example, the tension T may be a predetermined value, or may be an average of the tension of the web 50 over a predetermined period.

The controller 150 detects the displacement of the web 500 (step S20). For example, the edge detection sensor 160 measures the distance δ between the centerline Cr of the tensioning device 111 and the web 500, and then provides the measured distance to the controller 150.

Here, step S10 and step S20 may be performed simultaneously or sequentially, and step S20 is performed before step S10.

Next, reference tensions T1 and T2 applied to both ends of the dancer roll 111 are calculated by the controller 150 based on the tension T and the displacement δ of the web. Here, the tensions T1 and T2 may be calculated via equations 1 and 2 above, and the calculated tensions T1 and T2 are to be reference tensions, because the calculated tensions T1 and T2 are standard tension values measured at both ends of the dancer roll at the current tension T and displacement δ of the web.

After calculating the reference tensions T1 and T2 at both ends of the roll, the controller 150 independently controls the dancer moving part 120 at both ends of the dancer roll 111 based on the reference tensions, and thus the tension of the web 500 can be independently controlled.

Although exemplary embodiments of the present invention have been described, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one of ordinary skill in the art within the spirit and scope of the present invention as hereinafter claimed.