JP2005103889A - Gravure printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality gravure printing plate which can represent gradation-rich/fine characters and lines of image view and shows high registering precision and has no defects due to refuse or the like. <P>SOLUTION: This gravure printing plate is constituted of main cells 10 which are variable in size, the maximum size being defined by the number of screen lines and the minimum size being as specified allowing the transfer of ink to be successfully performed and fine subcells 20 which are disposed between the main cells 10, with the ratio of aperture area represented by 1 to 3% of the fine subcells 20. In addition, the fine subcells 20 are each arranged between the main cell 10 and the main cell 10 and disposed at 45° in a rotating direction to the disposition of the main cells 10 in such a way that the interval X between the disposition rows of the fine subcells 20 is equivalent to 1/√2 of the interval Y between the main cells 10. The fine subcells 20 are arranged in a region where the ratio of aperture area of the main cells 10 is equivalent to not more than 60 %. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gravure printing plate used for gravure printing, and more particularly to a gravure printing plate that smoothes gradation expression of printing.

  Conventionally, gravure platemaking methods are roughly classified into corrosion methods represented by conventional gravure and mechanical engraving methods. Among the corrosion methods, the conventional gravure method uses a white line screen on carbon tissue and creates a gradation expression by varying the depth of the plate by baking a continuous tone positive. Moreover, the net gravure method which improved that the stability of the continuous tone film is low is also used. As the halftone gravure method, the depth is the same and only the opening area of the cell is changed to express gradation (hereinafter referred to as the Porschel method), or a diffusion film is used when baking halftone dots, and the depth along with the opening area. The plate making method (hereinafter referred to as the TH gravure method) is also used, but this TH gravure method can change both the opening area and the depth at the same time, so the gradation expression is rich and the quality requirement It is used for high printed matter (for example, see Non-Patent Document 1).

  The mechanical engraving method, on the other hand, converts the shading of the document into the engraving depth of the diamond needle and engraves it. By using a triangular pyramid needle, the depth and opening size of the engraving cell can be changed simultaneously. . There is also a method of forming a hole by directly sublimating metal on a cylinder using a laser beam or an electron beam.

  The difficulty of the mechanical engraving method is the drawing of linear objects such as characters and ruled lines. Since the principle is that the dots are mechanically arranged, the straight line may appear to be a collection of rough dots, and the problem is that it is inferior in appearance in magazines that require character quality. In order to increase the resolving power by mechanical engraving, the engraving dots can be made finer. However, if each cell is made smaller, the engraving depth becomes smaller as the opening area is reduced, so that the concentration is as a whole. It was also a problem that the printing was lowered.

  In that respect, the corrosive method can sufficiently reproduce the linear data and the linear data of characters, and can form a plate with a depth that cannot be obtained by the mechanical engraving method. It can also be reproduced. However, in the corrosion method, it is necessary to output a positive film first and then expose it to a photoresist such as carbon tissue, which may cause burning of dust during exposure, misregistration due to misalignment of the positive and expansion, etc. It was a problem.

  In addition, a method of forming cells by developing and corroding in recent years has emerged and has become widespread by changing the exposure part of the above-mentioned Porschel method to scanning laser light and directly exposing the digitized image data to halftone dots. . As a result, fine lines and characters that cannot be expressed by mechanical engraving can be expressed with the same quality as conventional corrosion methods, and high-quality cylinders that are not affected by burning of dust or expansion and contraction of positive film can be produced. However, in this method, since the cell depth is constant and the gradation needs to be expressed only by the opening area of the cell, it has been found that it is difficult to express the TH gravure gradation using the porschel dot.

The relationship between the plate type and the gradation expression is shown in FIGS. FIG. 3 is a schematic diagram of the conventional method, which is composed of cells having the same area ratio over the shadow, intermediate, and light density regions. The shading of printing is represented by an increase or decrease in cell depth. The smooth gradation expression of the conventional method is a phenomenon that occurs because the ink spreads beyond the bank of the cell, and the fact that the bank between the cells is always constant and narrow is the cause of the spread of the ink. FIG. 4 is a schematic diagram of the TH gravure method. In this case, both the area and depth of the cell are increased or decreased to express the density of printing. It can be seen that an irregular cell across the shadow, middle, and light touches the next cell through the bank. For this reason, the halftone dot of printing is expressed as a group in which several cells are connected, and smooth gradation expression is possible. FIG. 5 is a schematic diagram of the Porschel method or the laser drawing method. In this case, the cell depth does not change in most regions, and the shade of printing is expressed by the change in area. In this Porschel method or laser drawing method, the printed halftone dots are made up of independent cells, and the cells are separated from each other in areas other than the shadow, so compared to the conventional method and TH gravure method. The phenomenon that halftone dots are expressed in groups did not hold, and the smooth gradation was inferior.

  Gravure printing plates have been developed to obtain this smoothness of gradation. This is related to the engraving method, and is intended to give a “fluctuating element to the shape and size of the cell” by adding a noise component to the image data.

  However, smooth gradation such as the conventional method and TH gravure method has not been obtained (for example, see Patent Document 1).

  In addition, there is a technique for realizing a smooth gradation expression by providing a main concave portion for forming an image and a non-thickness sub concave portion in which ink transfer does not occur or is extremely small by another method. . In this method, for example, the number of lines of the sub-recesses is exactly √2 times the number of lines of the main recesses, the screen angle of the sub-recesses rotates the main recess screen angle 45 degrees, and between the main recesses is accurate. When the sub-recesses are arranged on the screen, it may be effective for smooth gradation, but the number of lines and the arrangement may be slightly shifted to form a striped pattern similar to moire, which may not be preferable. (For example, see Patent Document 2).

The above prior art documents are shown below.
History of Gravure Technology Development-60 Years History and Current Status-Published April 1, 1979, (Printing Society Press) JP-A-10-264350 Japanese Patent Laid-Open No. 11-342679

  The present invention solves the problems of the prior art, and the problem is that the conventional gravure plate making method does not satisfy all of them, and there are abundant gradations and fine characters and image lines. It is to provide a high-quality gravure printing plate that can express image quality and is free of defects due to dust and the like.

  In order to achieve the above object in the present invention, first, in the invention of claim 1, a main cell whose size is variable and whose maximum is defined by the number of screen lines, and a minute cell disposed between the main cells. In a gravure printing plate comprising subcells, the microsubcells are arranged at an angle of 45 degrees with respect to the main cell array, and the interval is 1 / √2 of the main cell interval, and between the main cell and the main cell. It is set as the gravure printing plate characterized by being arrange | positioned.

  According to a second aspect of the present invention, there is provided the gravure printing plate according to the first aspect, wherein the minute subcell has an open area ratio of 0.1 to 3%.

  Furthermore, in the invention of claim 3, the arrangement of the minute subcells is a region where the opening area ratio of the main cell is 60% or less. The gravure printing plate according to claim 1 or 2, It is.

  Since this invention is the above structure, there exist the following effects.

  That is, according to the first aspect of the present invention, in a gravure printing plate comprising a main cell whose size is variable and whose maximum is defined by the number of screen lines, and a small subcell arranged between the main cells. The small subcells are arrayed by 45 degrees with respect to the array of the main cells, and the interval is 1 / √2 of the interval between the main cells, and is arranged between the main cell and the main cell. By spreading the ink in the cell, the ink in the micro sub-cells will promote the connection of the halftone dots. Therefore, by printing the halftone dots as a group instead of independently and expressing the smooth gradation, There is an effect that a high-quality gravure printing plate can be provided.

  Further, according to the invention according to claim 2, by setting the opening area ratio of the minute subcell in the range of 0.1 to 3%, the density of the entire printed matter is not affected, and the cell and the cell are separated. It has the effect of fulfilling the role of connecting well.

  Furthermore, according to the third aspect of the present invention, by arranging the minute subcells only in the region where the opening area ratio of the main cells is 60% or less, the subcells can be stably arranged and formed. Therefore, it is possible to provide a high-quality gravure printing plate that can promote smooth gradation expression by promoting the ink of the minute subcells arranged between the main cells to spread the ink of the main cells. This can be obtained by dividing the area of the gravure plate by dividing the area of the engraved portion of the gravure printing plate (cylinder) by the area of the observation region. In this case, the opening area ratio of the gravure printing plate is maximized at about 70% to 75%. In the region where the opening area ratio exceeds 60%, the bank width of the main cell is not so large as to prevent the ink from spreading, so that no minute subcell is required. Further, when the opening area ratio is about 70%, the bank width is about the same as the size of the minute sub cell, so that it becomes difficult to form the sub cell between the main cell and the main cell. For the above reasons, the subcell can be stably arranged and formed if the area ratio is 60% or less.

  Further, as a secondary effect, according to the present invention, the conventional halftone dot is expressed by the number of lines of the main dot, and the main dot and the minute subdot are expressed by the number of lines of each of the present invention. An image can be expressed with halftone dots of the number of lines, and a double high image quality can be obtained without using a high-resolution image with a large amount of data.

  Therefore, according to the present invention, a high-quality gravure printing plate that can express so-called abundant and smooth gradation that has not been satisfied with all the conventional gravure printing plates, and has high registration accuracy and no defects due to dust, etc. Can be provided.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1A shows a schematic view of a gravure printing plate of the invention according to claim 1. The main cell (10) and the minute sub cell (20) are arranged over the shadow, middle, and light areas. For example, as shown in FIG. 1B, this arrangement is arranged at 45 ° rotation with respect to the arrangement of the minute subcells (20), and the interval (X) between the minute subcells (20) is the main cell (10). The interval (Y) is 1 / √2, and the minute subcell (20) is arranged between the main cell (10) and the main cell (10).

  The size of the small subcell (20) can be changed within the range of 0.1 to 3% as necessary in accordance with the change of ink transferability due to the difference in paper. it can. By setting the opening area ratio of the minute subcells in the range of 0.1 to 3%, the density of the entire printed matter is not affected, and the cell is connected well.

  The printing gradation corresponds mainly by changing the area ratio of the main cell. However, since there is no difference between the size of the minute subcell (20) on the write side, the main cell (10) and the minute subcell (20 ) To create a gradation curve. Further, by increasing the number of minute subcells (20), it is possible to express smooth gradations that cannot be expressed by increasing the area of the main cell (10).

  Based on a positive document having the above information, plate making can be performed by a conventional porshell method, or a film forming surface on which a photosensitive film is formed can be exposed and developed based on digital plate information, or laser ablation can be performed. It is possible to obtain a gravure printing plate of the present invention by performing laser ablation on a film-formed surface on which a film is formed, then etching a metal surface exposed by development or laser ablation, then stripping the resist, and then providing hard chrome plating. it can.

  The gravure printing plate of the invention according to claim 2 will be described. As shown in FIGS. 1 (a) and 1 (b), the main cell (10) and the minute sub cell (20) are arranged in a region having an opening area ratio of 60% or less, and the size of the minute sub cell (20). The size can be changed if necessary in response to changes in ink transfer properties due to differences in paper. The print gradation corresponds mainly by changing the area ratio of the main cell (10). However, since there is no difference between the size of the minute subcell (20) on the right side (R), the print gradation is different from that of the main cell (10). The gradation curve is created from the sum of the minute subcells (20) as in the conventional method. In the area where the opening area ratio exceeds 60%, that is, the shadow side (S), the bank width of the main cell (10) is not so large as to prevent the ink from spreading, so the minute subcell (20) is not necessary. Further, when the opening area ratio is about 70%, the bank width of the main cell (10) becomes about the same as the size of the minute sub cell (20), so that the minute sub cell is between the main cell (10) and the main cell (10). It becomes difficult to form the cell (20). For the above reasons, the minute subcells (20) can be stably arranged and formed as long as the area of the opening area ratio is 60% or less.

  FIG. 2B shows a printed matter printed by the conventional method, and FIG. 2A shows a printed matter printed by the gravure printing plate of the present invention. According to this, in the conventional method of FIG. 2 (b), the connection between the halftone dots is not uniform and the gradation is not smooth, but according to the gravure printing plate of the present invention shown in FIG. 2 (a). In a printed matter, a smooth gradation can be expressed by connecting printing halftone dots of main cells to invisible subcell halftone dots.

The example of the gravure printing plate of this invention is shown, (a) is the cross-sectional schematic diagram and top view, (b) is the enlarged view showing the plane. (A) is an enlarged view of the printed matter by the gravure printing plate of this invention, (b) is an enlarged view of the printed matter by the conventional gravure printing plate. It is the cross-sectional schematic diagram and top view of the gravure printing plate by the conventional conventional method. It is the cross-sectional schematic diagram and top view of the gravure printing plate by the conventional TH gravure method. It is the cross-sectional schematic diagram and top view of the gravure printing plate by the conventional por shell method and the laser corrosion method.

Explanation of symbols

10 ... Main cell 20 ... Small subcell S ... Shadow side R ... Light side

Claims (3)

  In a gravure printing plate comprising a main cell whose size is variable and whose maximum is defined by the number of screen lines, and a minute subcell arranged between the main cells, the minute subcell is 45 to the arrangement of the main cell. A gravure printing plate comprising an array of degrees of rotation, the interval being 1 / √2 of the interval between main cells, and being arranged between the main cells and the main cells.   The gravure printing plate according to claim 1, wherein the minute subcell has an opening area ratio of 0.1 to 3%.   The gravure printing plate according to claim 1 or 2, wherein the arrangement of the minute subcells is a region having an opening area ratio of the main cell of 60% or less.