JP2004284295A - Gravure printing roll and gravure printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gravure printing roll in which an AM screen cell and an FM screen cell are formed on one roll, and a gravure printed matter. <P>SOLUTION: A cell corresponding to a letter and a lettering image and the like requiring a high ink concentration is formed with an AM screen, while a cell corresponding to a photo image and a fine line expressed in graduation is formed with an FM screen on one roll. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gravure printing roll and a gravure printed matter in which an AM screen cell and an FM screen cell are formed for one roll.
[0002]
[Prior art]
FIG. 2 shows a normal gravure AM screen (Amplitude Modulation Screen). In the gravure plate, the gradation expression is represented by the size of a halftone dot, and it is necessary to put the ink into a cell with a doctor and scrape off excess ink, so that the area of the screen line at the shadow portion becomes 20% to 30%. That is, the gravure plate is configured as a plate that expresses the gradation of the printed matter at about 0 to 75% with respect to the gradation of the printed matter of 0 to 100%.
The gravure plate includes a method of forming cells by engraving and a method of forming cells by applying, exposing, developing, and etching a photosensitive film (hereinafter, referred to as an etching method). Since it is formed in the shape of a pyramid, the transfer of the ink in the highlight portion is good. In the etching method, since the cells are formed in shallow dish-shaped concave portions, the transfer of the ink is inferior to the engraving method due to the ink being clogged in the cells in the highlight portion where the cells are very small. On the other hand, there is an advantage that the ink can be reliably transferred to the intersection by cutting off the intersection of the screen lines of the uppermost shadow portion so that the ink flows, and the outline of the character can be made an outline without jagged. Since the cells in the shadow area are also shallow, they are suitable for printing using water-based ink.
[0003]
FIG. 3 shows an AM screen of an offset printing plate or a flexographic printing plate. An AM screen such as an offset printing plate also expresses a gradation expression by the size of a halftone dot, but unlike a gravure plate, a screen line is not required. Therefore, the gradation of a printed matter is approximately 0 to 100%, and the gradation of a plate is approximately 0 to 100%. Corresponds exactly.
[0004]
In recent years, in the field of offset printing and flexographic printing, as shown in FIG. 4, an FM screen method for expressing a gradation expression by the number of minute halftone dots has been mainly used in Europe and the United States instead of the conventional AM screen method shown in FIG. It is starting to be put to practical use. Since the FM screen technology can obtain the resolution of the minimum drawing dot that uses the fine structure expression power, the image quality is expected to be improved even in the output from a low-resolution output device such as a printer or an on-demand printer. In gravure printing, there has been no attempt to apply the gravure printing because there is no screen line for putting ink into a cell with a doctor and scraping off excess ink.
[0005]
The following is an excerpt of the advantages of the FM screen method applied in the fields of offset printing and flexographic printing, which are published on the Internet by the Japan Printing Industry Federation.
(1) Since the FM screen is not regularly arranged in the halftone dot shape unlike the screen (FIG. 3), it is possible to avoid occurrence of moiré which may be an obstacle. In the AM screen, the screen angle is set for each plate so that the output moire is minimized. However, in the FM screen, the output moire does not occur because dots are scattered. The FM screen does not generate a rosette pattern. On the AM screen, a pattern of a turtle pattern appears from the highlight to the middle, but this does not occur on the FM screen. No line break occurs even when printing five or more colors.
(2) The FM screen can reduce the halftone dot size over all gradations from highlight to shadow, so that high-resolution print reproduction can be performed. The screen is distributed without the minimum dots sticking up to about 30% density.
(3) Density jumps are not noticeable on FM screens. Density jumps (steps in density) occurring at halftone dots near 50% on the AM screen are inconspicuous on the FM screen. This is because the halftone dots near the middle of the screen make random contact with the adjacent points, so that the density step is reduced.
(4) The color tone of the FM screen is vividly expressed. Colors close to the primary colors and colors with high saturation can be reproduced with the four process colors, and a more realistic expression effect can be exhibited.
(5) The FM screen can have a higher resolution than the AM screen if the output data capacity is the same. Since the interval between the halftone dots can be reduced, if the output data capacity is the same, the resolution can be made higher than that of the AM screen by reducing the dot diameter. Since the minimum drawing dot has a physical resolution in the FM screen, it can be expected that image data (32 to 51% of the screen) is smaller than that of the screen. Since the dot diameter can be increased to obtain the same resolution as that of the 175-line AM screen, the FM screen created from the same input data amount requires a relatively small image data amount. For this reason, if the quality equivalent to the screen of 175 lines can be realized with an FM screen having a large dot diameter, the processing time and waiting time of the plate making / outputting step can be reduced, and the productivity can be improved.
(6) In the FM screen, the minimum drawing dot becomes the physical resolution, and it is easier to obtain a higher resolution than the AM screen. As for the number of gradations, the number of gradations decreases at a high screen line number in order to realize high definition on an AM screen, but the FM screen does not have such a case.
(7) The tone of the middle to shadow parts of the FM printed matter is higher than that of the AM printed matter, and the highlight to the middle part is almost equal to or lower than AM. The FM value of the K value representing the contrast on the shadow side is generally small. Regarding the ink solid density, in a high definition FM screen using a small dot diameter, it is difficult to obtain a high density in a halftone portion similarly to an AM screen having a high screen ruling.
[0006]
Conventional gravure printing rolls are all formed of AM screen cells, and none of the gravure printing rolls are formed of FM screen cells. With the engraving method, it is impossible to engrave an FM screen, but with the photolithography method there is a possibility.
Further, in the conventional gravure printing roll, there was no one in which an AM screen cell and an FM screen cell were formed for one roll.
In the specification of the present application, the cell of the AM screen is made by laser plate making including the steps of photosensitive film coating-laser exposure / latent image formation-development-etching, the arrangement pitch is constant, and the cell size changes. Refers to both cells and cells made with a diamond stylus of an electronic engraving machine and having a constant arrangement pitch and varying cell size and depth, and other cells having a constant arrangement pitch. .
[0007]
Conventionally, a gravure plate that requires sharpness of the outline of a character or a gravure plate that requires a sufficient density in a shadow portion has a laser plate consisting of a photosensitive film coating-laser exposure / latent image formation-development-etching process. Gravure plate making by an electronic engraving machine, which causes less transfer failure due to ink dropout, is often used for images that are frequently used and have many photographic portions.
Also, in making a plate for multi-color printing gravure printing, there are cases where a character / thin line plate is used for a net gravure and a plate having a photographic portion is used for an electronic engraving machine, taking advantage of the features of each plate making.
However, there is an image in which moiré occurs when the engraving plate and the net gravure plate making are combined carelessly, and there is a limitation on use. For one cylinder, both plate making methods can be used, for example, an electronic engraving machine can be used for the photographic part and a plate gravure method can be used for the character / thin line part. There were problems such as an increase in man-hours and an increase in cost in practical use.
[0008]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned point, and makes it possible to apply an FM screen applicable to offset printing or the like to gravure printing and further combine it with an AM screen to compensate for each other's drawbacks. It is an object of the present invention to provide a gravure printing roll and a gravure printed matter that can obtain high-definition gravure printing as compared with a case where printing is performed using a gravure printing roll having cells of the formula (1).
According to the present invention, the problem of insufficient density caused by using an FM screen can be avoided by using an AM screen. In addition, poor transfer of ink in a highlight portion caused by the use of an AM screen, a thin inclined line or a contour of a curved line can be avoided. An object of the present invention is to provide a gravure printing roll and a gravure printed matter which can avoid the problem of unclearness and moire generation by using an FM screen.
[0009]
[Means for Solving the Problems]
According to the present invention, cells corresponding to characters and lettering images requiring a high ink density for one roll are formed on an AM screen, and a photographic image and a thin line cell expressed by gradation are FM-based. A gravure printing roll characterized by being formed by a screen.
According to the invention described in [Claim 2], it is possible to provide a gravure printed matter characterized by being gravure printed using the gravure printing roll according to [Claim 1].
According to the present invention, cells corresponding to characters and lettering images requiring a high ink density are formed on an AM screen, so that a sufficient ink density is ensured as necessary. By forming the line cells with the FM screen, the FM screen is superior to the AM screen in that the advantage is that moiré can be avoided, line breaks do not occur even in printing of five or more colors, and high resolution. It is possible to provide a gravure printing roll and a gravure printed matter printed using the gravure printing roll, which can enjoy advantages such as print reproduction and inconspicuous density jump.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
In the gravure printing roll of the present invention, cells corresponding to a character 1 and a lettering image 2 that require a high ink density for one roll R are formed on the AM screen shown in FIG. 2 and expressed by gradation. The cells of the photographic image 3 and the thin lines 4 are formed by the FM screen shown by C1 in FIG.
[0011]
The AM screen shown in FIG. 2 may be formed by any of a method of forming a cell using an electronic engraving machine and a method of forming a cell by applying, exposing, developing, and etching a photosensitive film.
[0012]
In FIG. 3, A1 represents digital information of an FM screen obtained by performing FM screening using an FM screening program when a gradation of 0% to 100% is prepared as plate information before forming a plate. It is. B1 is a screen line of the most shadow portion of the AM screen obtained by performing AM screening on the plate information before forming the plate and corresponding to the shadow region from the shadow region or the shadow portion of the halftone portion. This is a display of the displayed AM screen information. C1 displays digital version information in which digital information of the FM screen shown in A1 and digital information of only the screen lines of the AM screen shown in B1 are superimposed.
[0013]
Accordingly, the plate C1 performs FM screening of the region from the highlight to the shadow with respect to the plate information before the plate is formed, so that the minimum cell has a required size for performing good ink transfer. In the area from the shadow portion of the halftone portion to the shadow portion of the FM screen information A1 (illustrated as optical information), information B1 (optical information) of only the screen line of the most shadow portion of the gravure AM screen is displayed. (Shown as information) are superimposed on each other, so that the area from the highlight area to the halftone area is purely an FM screen and has no graininess. The size of the screen is regulated to the required size which is satisfactorily performed. In the area of the part are completely become a gravure printing plate will AM screen.
[0014]
The FM screen shown as plate C1 in FIG. 3 is formed by a method of forming cells by applying a photosensitive film, laser exposure, development, and etching, or by a method of forming cells by laser engraving. .
Since an FM screen cannot be made by an electronic engraving machine, a plate in which an AM screen and an FM screen are mixed is formed by a method of forming a cell by applying a photosensitive film, laser exposure, development, etching, or laser engraving. It is preferable that the cell is formed by any of the cell forming methods by the method because no man-hour is required.
[0015]
This gravure printing plate is a mesh-shaped AM screen required for gravure printing in the shadow area, and the FM density of the screen is in the grid, and the optical density is uneven. In the area that shifts from the halftone area to the halftone area, the mesh-shaped AM screen gradually disappears and shifts to the dots of the FM screen. From the halftone area to the highlight area, the shadow area of the gravure version of the AM screen has the highest shadow area. Since the screen is not superimposed, the screen is purely an FM screen. In addition, since the minimum cells are regulated to a required size that allows good ink transfer, the ink transfer is good and the FM screen is excellent. Points are obtained.
[0016]
In the plate making method, the digital plate information is separated into three colors of Y, M and C, and the area from the highlight part to the shadow part is reduced to a required size so that the minimum cells can transfer ink well. The FM screening is performed by the improved program which is regulated to obtain plate information, and the AM screening is performed by the improved AM screening program, and from the shadow portion to the shadow portion of the halftone portion, the highest shadow portion of the gravure AM screen is obtained. The plate information indicated by the screen is obtained, the two plate information are superimposed, and the plate is made based on the plate information.
[0017]
【The invention's effect】
As is clear from the above description, the present invention
Cells corresponding to characters and lettering images requiring a high ink density for one roll are formed on an AM screen to ensure a sufficient and sufficient density of the ink and are expressed in gradation. By forming photographic images and cells with fine lines on FM screens, FM screens are superior to AM screens. One advantage is that moiré can be avoided, and no line break occurs even when printing five or more colors. It is possible to provide a gravure printing roll and a gravure printed matter printed using the gravure printing roll, which can enjoy advantages such as high-resolution printing reproduction and inconspicuous density jump.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a gravure printing roll according to an embodiment of the present invention.
FIG. 2 is a view showing a conventional AM screen of a gravure plate used conventionally and used in the present invention.
FIG. 3 is a diagram showing gradation of an FM screen used in the present invention.
FIG. 4 is a diagram showing a normal AM screen used for conventional offset printing and the like.
FIG. 5 is a diagram showing an FM screen used for conventional offset printing and the like.
[Explanation of symbols]
R: roll, 1: character, 2: lettering image, 3: photographic image, 4: thin line,

Claims (2)

Cells corresponding to characters and lettering images that require a high ink density for one roll are formed on an AM screen, and photographic images represented by gradations and cells with thin lines are formed on an FM screen. A gravure printing roll characterized in that: A gravure printed matter obtained by gravure printing using the gravure printing roll according to claim 1.

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