KR20120016035A - Method and apparatus for providing precise printing using linear encoder - Google Patents

Abstract

PURPOSE: A precise printing method and apparatus which uses a linear encoder are provided to improve overlay accuracy of printing by controlling a traveling speed and/or a traveling direction of a web based on information which is provided from a read station. CONSTITUTION: A first printing unit(10) executing first printing on the surface of a web(1). The first printing unit comprises a pattern roll(11), a blanket roll(12), and an impression roll(13). A second printing unit(20) execute second printing on the surface of the web which is firstly printed. A linear encoder(30) is arranged between the first printing unit and the second printing unit. The linear encoder generates a sensing signal by sensing a cover of the web. A read station(90) determines a moving speed of the web based on the sensing signal generated from the linear encoder.

Description

Method and apparatus for providing precise printing using linear encoder

The present invention relates to a precision printing apparatus and method for performing a printing operation of 2 degrees or more, and more particularly, to print on paper, as well as to produce an electronic device such as a display panel or a solar panel through a printing operation. The present invention relates to a precision printing apparatus and a method which can be applied when the allowable error is very small compared to a conventional printing job while a printing job of 2 degrees or more is performed.

Existing methods for manufacturing semiconductors, such as exposure techniques, take days to weeks from design to fabrication and require significant expensive equipment and extreme processing techniques. Therefore, it is very difficult or impossible to implement a low cost electronic device using a conventional semiconductor process based on a silicon wafer.

In the future, there is a trend and forecast of international technology that low-cost consumable electronic devices such as RFID, solar cells and electronic paper will open new markets. This is not a replacement for the semiconductor process on a silicon substrate, but a new low-cost electronics market with a precision of several tens of micrometers by using a printing process on a paper or plastic substrate.

In addition, as display products are rapidly shifting to flat panel displays, which are spotlighted as next-generation displays such as LCD, PDP, organic EL, and FED, there is a fierce competition between manufacturers and the market leading competition between display methods. Accordingly, research into a new process method using a printing process is being actively conducted as a method for manufacturing a flat panel display panel at low cost.

In terms of materials, a low-cost process of directly printing a plastic substrate rather than an expensive silicon wafer at a low temperature such as an inkjet process, a gravure printing method, and a screen printing method is being studied. Rather, roll-to-roll printing processes are in the limelight to maximize productivity. Roll-to-roll printing is a contact printing method that directly transfers ink onto a substrate made of a thin film of plastic or metal by applying ink to a printing roll. The gravure method, the flexography method, and the offset ( Off-set). The technologies required for roll-to-roll printing process and equipment technology development are largely divided into printing process equipment technology and roll-to-roll web feed control technology.

One of the most important techniques for forming a multi-layer circuit in the roll-to-roll process is the inter-layer superposition accuracy. The overlapping accuracy in the direction perpendicular to the moving direction of the web depends on how precisely the web is guided. Roll-to-Roll Web Feeding Control Technology It refers to a technology that induces a web precisely to increase overlapping accuracy. In conventional web induction systems, the repeatability of stepping motors (typically ± 10 µm), the assembly errors and play of bearings and pivot systems (typically ± 10 µm), and the kinematics of meander control systems In consideration of the structure and the speed of the meander control, the stepping motor is controlled with an input of about 300% to 500% of the theoretical calculated value to achieve a meandering precision of 70 to 100㎛. However, these conventional commercialized equipments are still inferior in accuracy and insufficient in use in roll-to-roll equipment for printed electronics in terms of performance and cost is too high compared to the performance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and when providing electronic devices such as a display panel by a printing method, to provide a printing method and apparatus capable of precise web feed control, which is a decisive factor for improving the overlapping accuracy of printing. The purpose.

In order to solve the above-mentioned problems, a method of performing a precise printing using a linear encoder in a print job that is printing more than two degrees, (a) for detecting the linear encoder at a predetermined position of the print object in the first printing Printing a cover page; (b) detecting the mark printed in step (a) through a linear encoder; And (c) determining the moving direction and / or the moving speed of the print object based on the sensing signal generated by the linear encoder in step (b).

In the precision printing method according to the present invention, (d) before the second degree printing is performed, the moving direction and / or the moving direction of the print object based on the moving direction and / or the moving speed of the print object determined in the step (c). The method may further include adjusting the speed.

In the printing method according to the present invention, the position where the cover is printed on the printing object may be at least one edge portion of the printing object, and the cover may be arranged at regular intervals of marks having the same shape.

The print object is provided in the form of a sheet or a web.

Precision printing method according to the invention can be made by the offset printing method.

According to another aspect of the present invention, there is provided an apparatus for performing precise printing using a linear encoder in a printing job in which printing is performed at least two degrees, comprising: a primary printing unit for printing a cover sheet at a predetermined position of a printing object; A linear encoder for detecting the mark printed on a printing object; And a reading unit that determines a moving direction and / or a moving speed of the print object based on the signal generated by the linear encoder.

The precision printing apparatus according to the present invention may further include a control unit for adjusting the moving direction and / or the moving speed of the printing object based on the moving direction and / or the moving speed of the printing object determined by the reading unit.

According to the present invention, there is provided a printing method and apparatus for improving the overlapping accuracy of printing through precise web feed control.

1 schematically shows a precision printing apparatus according to the present invention;
2 is a view showing an example of a cover printed on a web surface by a primary printing unit in the precision printing apparatus according to the present invention.
3 shows an embodiment of a linear encoder used in a precision printing apparatus according to the present invention.
4 shows an output signal of the linear embodiment shown in FIG.
Fig. 5 shows another embodiment of the linear encoder used in the precision printing apparatus according to the present invention.
FIG. 6 is a diagram illustrating a converted digital signal in which the analog signal shown in FIG. 4 passes through a comparison circuit. FIG.
7 shows another embodiment of a cover printed on the web surface by a primary printing unit in the precision printing apparatus according to the present invention.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

1 schematically shows an offset printing apparatus according to an embodiment of the present invention. The printing apparatus performs second degree printing on a print object in the form of a web. Although the embodiment shown in FIG. 1 relates to a printing apparatus that performs second-degree printing, the present invention is not limited thereto and may be applied to any printing apparatus that performs two-degree or more printing. Further, in the illustrated embodiment, the print object may have a web form, but may also be applied when the print object has a sheet form.

In the embodiment shown in FIG. 1, the printing apparatus 100 includes a first printing unit 10 for performing primary printing, a second printing unit 20 for performing secondary printing, a first printing unit, and a second printing unit. A linear encoder 30 disposed between the printing units, and a reading unit 90 for receiving a signal from the linear encoder.

The web 1 to be printed is released from an unwinder 40 and put into a print job. The material of the web 1 to be printed may be any material as long as it can be printed in a print job using paper, plastic or other rolls. When the object to be printed is in the form of a sheet, another type of apparatus for supplying the object to be printed is used.

The first printing unit 10 includes a pattern roll 11, a blanket roll 12, and an impression roll 13. The pattern to be printed on the web 1 is provided on the pattern roll 11, and this pattern is printed on the web 1 via the blanket roll 12. The impression roll 13 acts to press the web 1 against the blanket roll 12.

The first printing unit 10 performs primary printing on the surface of the web 1 on which nothing is printed. When primary printing is made by the first printing unit 10, the front cover arranged in a predetermined manner is printed together on the surface of the web 1. This mark is for the linear encoder 30 to detect. 2 shows an example of such a marker 9. In the illustrated embodiment, the mark 9 has a form in which a plurality of straight lines having a predetermined length are arranged at regular intervals. However, as will be described later, the shape of the marker 9 is not limited to that shown in FIG. 2 and may be any shape as long as the linear encoder 30 can be used. This cover is preferably printed on the edge of the web 1. The front cover 9 may be printed on one edge portion of the web 1, more preferably on both edge portions.

The second printing unit 20 is likewise equipped with three rolls 21, 22, 23 and performs secondary printing on the surface of the web 1 on which primary printing is performed in the same manner as the first printing unit 10. To perform. In the case where the primary printing and the secondary printing are related, for example, when the secondary printing is to be performed on the upper portion of the area where the primary printing is made, the moving direction and the moving speed of the web 1 should be precisely controlled. . In particular, when the error recognized between the primary printing and the secondary printing is very small, such as when a circuit or an element such as a display or a solar cell is formed by a printing method, the accuracy of the secondary printing becomes very important.

The linear encoder 30 is disposed between the first printing unit 10 and the second printing unit 20. The linear encoder 30 senses the front cover 9 printed on the web 1 by the first printing unit 10. If the front cover 9 is printed on only one edge portion of the web 1, the linear encoder 30 is disposed on the corresponding side. If the front cover 9 is printed on both edge portions of the web, the linear encoder ( 30) is arranged. The linear encoder 30 transmits a signal generated by sensing the mark 9 to the reading unit 90. The reading unit 90 may be implemented as a single device or as a computer program.

As shown, the linear encoder 31 may be arranged after the secondary printing unit. In this case, the direction of the web can be controlled more precisely.

3 and 5 show an example of a linear encoder 30. 3 is a case where the print object 1 is optically transparent and FIG. 5 is a case where the print object is optically opaque. "Optically transparent" means a case where the light used by the linear encoder can transmit the print object, and "optically opaque" means a case where the light used by the linear encoder cannot pass the print object. .

In the embodiment shown in FIG. 3, the linear encoder 30 includes a light source 31, a condenser lens 32, a scanning grating 33, and a light sensing unit 34 composed of a plurality of photo cells.

Various things can be used as the light source 31. For example, an LED light emitting device or a laser light emitting device may be used as the light source. The light emitted from the light source 31 may be visible light or light in an area other than the visible light. The appropriate light source is selected according to the material of the web 1.

Light emitted from the light source 31 is collected by the condenser lens 32 and proceeds in parallel. When the light source 31 is placed at a position that is the focal length of the condenser lens 32, the light incident on the condenser lens 32 is emitted in parallel.

Light emitted in parallel from the condenser lens 32 passes through the scanning grating 33. The scanning grating 33 passes only a part of the light emitted in parallel from the condenser lens 32. In detail, the scanning grating 33 includes a plurality of slits 331, and passes a portion of light through the slits 331.

Light passing through the scanning grating 33 is irradiated to the web 1 surface. Since the cover 9 is printed on the surface of the web 1 as shown in FIG. 2, as the web 1 proceeds, light is blocked from passing through the web 1 or transmitted by the cover 9. do. That is, when light is irradiated to the portion where the front cover 9 is not printed on the surface of the web, the light passes through the web 1, and when the front cover 9 is irradiated to the printed section on the surface of the web 1 It is blocked by the mark 9 so as not to penetrate the web 1.

On the other hand, the slit 331 of the scanning grating 33 is composed of at least two sets. In the illustrated embodiment, two sets of slits are provided, and the first set of slits and the second set of slits are arranged as follows. That is, when light passing through the first set of slits passes through the web without being blocked by the cover of the web, the light passing through the second set of slits is blocked by the cover so that at least some or all of the slits do not penetrate the web. Is formed. According to a method of disposing the first set of slits and the second set of slits, the relationship between the detection signals of the photocells included in the photodetector 34 varies as described below.

The light sensing unit 34 is composed of a plurality of photo cells and is disposed on the opposite side to the side where the light source 31, the condenser lens 32, and the scanning grating 33 are arranged based on the web 1. In the illustrated embodiment, the light detector 34 includes two photo cells. The number of photo cells corresponds to the number of sets of slits in the scanning grating. That is, in the case of four slit sets, the light detector 34 includes four photo cells. In addition, the number of slit sets may vary depending on the shape of the cover page printed on the web 1.

Each photo cell senses light transmitted through the web 1. In the illustrated embodiment, the first photocell senses light passing through the web after passing through the first set of slits in the scanning grating, and the second photo cell passes through the web after passing through the second set of slits in the scanning grating. Sensing transmitted light As described above, when all the light passing through the first set of slits passes through the web, the light passing through the second set of slits is blocked at least in part or all by the marker on the web. For example, the slits of the scanning grating may be arranged such that the output of the sensing signal A of the first photo cell and the sensing signal B of the second photo cell has a phase difference of 90 degrees as shown in FIG. 4.

The reading unit 90 reads the moving direction and / or the moving speed of the web based on the signal received from the light sensing unit 34 of the linear encoder 30. The reading unit 90 processes the received signal in an analog or digital manner. When the signal of the linear encoder 30 is given as described above, the moving distance of the print object can be known. The related art reading technique of the linear encoder can be applied to what is known in the art. Also, when the moving distance is determined, the moving speed of the print object can be known.

If the front cover 9 is printed on only one edge portion of the web, the moving speed of the web can be measured in the manner described above. On the other hand, a positioning cover having a different form in addition to the cover as shown in FIG. 2 may be printed on the web 1. In this case, since the shape of the detection signal of the linear encoder 30 is different, the reading unit 90 can read the position of the positioning mark. This positioning mark is printed on the web 1 at regular lengths such as 2 m or the like, or is printed at each manufacturing unit length of the display panel, for example. The reading unit 90 may measure how much the current web 1 has progressed from the last positioning mark by using the detection signal of the linear encoder 30.

In the case where the front cover 9 is printed on both edge portions of the web 1, the readout unit 90 reads the web 1 as well as the moving speed of the web 1 from the detection signals received from both linear encoders 30. The moving direction of can also be read. In other words, the movement read by the signal transmitted from the linear encoder 30 disposed on one side of the web 1 and the movement read by the signal transmitted from the linear encoder 30 disposed on the other side of the web 1. By comparing the distances, it is possible to determine whether the web 1 is moving in the straight direction or the inclined direction. If the distances determined by the signals transmitted from the linear encoders on both sides are the same, the web is determined to move in a straight line direction. If the distances determined by the signals transmitted from the linear encoders on both sides are different, the web is inclined direction. It is judged to move to. That is, the web is inclined to move toward the direction where the moving distance is short.

The reading unit 90 may transmit the determination result to the control unit 90 of the printing apparatus. In the illustrated embodiment, the computer is shown to perform both reading and control operations. The controller 90 may control the adjusting devices 61, 62, 63, 64, 65, and 66 of the printing apparatus to adjust the moving direction and the moving speed of the web. For example, when the web moves in an inclined direction, the web is guided again in a straight direction by using lateral guide rolls 61 and 64.

5 shows a technical configuration of a linear encoder that can be used when the material of the web does not transmit light of the linear encoder.

In the linear encoder shown in FIG. 3, since the light emitted from the light source could penetrate the web, the label printed on the web was used for the purpose of blocking the light transmission. In the embodiment shown in Fig. 5, since the web does not transmit light, the label is used for the purpose of reflecting light. However, when the material of the web reflects light of the linear encoder well, the label may be used for the purpose of not absorbing and reflecting the light as in the above-described embodiment. That is, according to the light reflection characteristic of a web, a label can be printed using the pigment from which an optical characteristic differs.

In comparison with the embodiment shown in FIG. 3, an optical splitter 35 is further disposed between the condenser lens 32 and the scanning grating 33, and the light sensing unit 34 is disposed on the same side as the light source 31. do. Of the light passing through the slit of the scanning grating 33, the light reflected from the marker 9 is guided in a direction orthogonal to the light incident by the light splitter 35. The guided light is detected by the photo cell of the light detector 34. Accordingly, an output signal having the same shape as that of the linear embodiment of the above-described form can be obtained.

On the other hand, while the conventional art related to the linear encoder uses the analog signal shown in FIG. 4, the analog signal may use a digital signal passed through a comparator circuit or both signals. A signal when the analog signal shown in FIG. 4 has passed through a comparator circuit is shown in FIG. Therefore, the shape of the label can be modified to generate a signal such as the signal shown in FIG. For example, when the front cover shown in FIG. 7 is printed on the surface of the web and the signal detected by the photo cell is digitized, a digital signal as shown in FIG. 6 may be obtained. The shape of each mark forming the mark and the interval between the marks can be adjusted to output the digital signal shown in FIG. In this case, the photocells of the linear encoder are arranged to correspond to the positions of the marks. That is, in the embodiment shown in FIG. 3, the photocells are arranged back and forth in the direction of travel of the web. However, when detecting a sign as shown in FIG. 7, the width of the web is perpendicular to the direction of travel of the web. The photo cell is arranged in the direction.

2 and 7 is just one embodiment of a cover printed on the web in the printing apparatus according to the present invention, the linear encoder technology that can read the moving distance or speed of the web All signs are applicable.

Hereinafter, a method of performing a print job in the printing apparatus according to the above-described embodiment will be described.

A printing operation of 2 degrees or more is performed for a print object having a web form or a sheet form. In the printing apparatus according to the exemplary embodiment of the present invention illustrated in FIG. 1, second-degree printing is performed on a web-type print object, and the first and second printing units perform a print job in an offset manner.

The web is second degree printed while passing through the primary and secondary printing units. The primary printing unit additionally prints the cover page at a predetermined position on the web surface while performing the printing operation required on the web surface. The label may be of any type as long as it can be used by the linear encoder, including the form shown in FIG. 2 or 7. In this embodiment, a cover is printed on one edge portion or both edge portions of the web.

The secondary printing unit performs the secondary printing operation on the surface of the web on which the primary printing is made. When the object to be printed is an electronic device such as a display panel or a solar cell panel, precise printing is required. That is, the relative position of the area where primary printing is made and the area where secondary printing is made should coincide within a very small error range compared to the design.

The linear encoder disposed between the primary print unit and the secondary print unit senses a mark printed by the primary print unit. The signal output from the linear encoder is transmitted to the reading unit.

The reading unit determines the moving speed of the web based on the signal received from the linear encoder. When the cover is printed on only one edge portion of the web, the reader can determine the moving speed of the web, and when printed on both edge portions of the web, the reader can determine the direction of movement of the web based on signals from both linear encoders. Can be. That is, when the movement speed of one is faster than the movement speed of the other by comparing the signals detected by the linear encoder from the marks printed on both edges of the web, the web is inclined toward the faster movement speed.

The reading unit may transmit information about the moving speed and / or the moving direction of the web to the control unit of the printing apparatus. The controller may adjust the moving speed and / or the moving direction of the web based on the information received from the reading unit. For example, when it is determined that the moving direction of the web is inclined, the moving direction of the web may be corrected using a meander control roll.

In the above embodiment, the printing apparatus has been described as using an offset method, but the precision printing method according to the present invention can be applied to any printing apparatus that performs printing of 2 degrees or more.

Although the invention has been described in detail based on the embodiments shown in the accompanying drawings, it is apparent that various modifications are possible without departing from the scope of the invention. Nothing described herein is intended to narrow the scope of the invention to the scope of the appended claims. The foregoing examples are for illustrative purposes only and are not intended to exclude those having other embodiments.

1: website
9: cover
10, 20: printing unit
30, 31: linear encoder
40: Unwind
50: Rewinder
61-66: Web progress control device
90: reading and control

Claims (7)

As a method of performing precise printing using a linear encoder in a print job in which two or more degrees of printing are performed,
(a) printing a cover for sensing by the linear encoder at a predetermined position of the object to be printed in the first printing;
(b) detecting the mark printed in step (a) through a linear encoder; And
(c) determining the moving speed of the print object based on the detection signal generated by the linear encoder in step (b);
Including,
The indicia printed in step (a) comprises a first portion and a second portion, and the detection signal generated by the linear encoder in step (c) is a digital signal and is the first by the first portion of the indicia. A sensing signal and a second sensing signal by the second portion, and a position where the first portion and the second portion of the cover are printed is the same as that of the first sensing signal and the second sensing signal, but are shifted from each other. Placed to have a phase
Precision printing method. The method according to claim 1,
and (d) adjusting the moving speed of the print object based on the moving speed of the print object determined in step (c) before the secondary printing is performed. The method according to claim 1,
The position at which the cover is printed on the printing object is a precision printing method, characterized in that at least one edge portion of the printing object. An apparatus for performing precise printing by using a linear encoder in a print job of two or more degrees of printing,
A primary printing unit for printing a cover sheet at a predetermined position of the object to be printed;
A linear encoder for generating the detection signal by detecting the mark printed on a printing object; And
A reading unit that determines a moving speed of a print object based on the detection signal generated by the linear encoder
Including,
The indicia printed by the primary printing unit includes a first portion and a second portion, and the detection signal generated by the linear encoder is a digital signal and the first detection signal by the first portion of the indicia. And a second sensing signal by the second portion of the marker, wherein the first portion and the second portion of the marker are arranged such that the first sensing signal and the second sensing signal have the same period but are out of phase with each other.
Precision printing device. The method of claim 4,
A control unit for adjusting the moving speed of the printing object based on the moving speed of the printing object determined by the reading unit
Precision printing device further comprises. The method of claim 4,
The first portion of the cover and the second portion of the cover are each made of a plurality of rectangular shaped marks are arranged at regular intervals along the direction of the print object,
The marks of each rectangular shape of the first part of the cover and the marks of each rectangular shape of the second part of the cover are arranged to be shifted by a predetermined degree.
Precision printing device, characterized in that. The method of claim 6,
The linear encoder includes at least one light source for irradiating light to the label, a first detector for detecting light generated by the light emitted by the light source acting with the first portion of the label, and the light source. And a second detector for detecting the light generated by the irradiation of the light with the second portion of the label.
Precision printing device, characterized in that.

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