JPS5834454A - Preparation of screen - Google Patents

Abstract

PURPOSE:To form a gravure screen causing no moire and no roughening, by using a pattern obtained by correcting figures consisting of irregular polygons formed by deforming polygons so as to give each polygon an area in a specified range. CONSTITUTION:Each intersection point of a pattern, as shown in dotted lines, consisting of 2-dimensionally connected squares is moved randomly, and each point obtained is joined in response to the initial intersection points, resulting in forming a figure consisting of irregular quadrilaterals, as shown in full lines. Then, the areas of the quadrilaterals are corrected to be within a specified range by adding a new line segment to each too large one, as shown in a thick full line, and removing a line segment joining the intersection points from each too small one, as shown in a dotted line, thus permitting a screen to be formed using the obtained pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screen, and more specifically, the present invention relates to a screen, and more particularly, to a method for preventing moiré between gravure screens, between a gravure screen and a regular pattern of positive patterns, or between a gravure screen and a net positive pattern. The present invention relates to a gravure screen that can prevent 1]-.

In order to perform gravure printing, a so-called constrictor is generally required to form four independent microscopic reservoirs for holding ink on the surface of the gravure plate. It is well known that a gravure screen is used to form such minute recesses. Gravure screens generally have a large number of opaque independent tiny dots regularly arranged1, and when printing two or more colors using such a gravure screen, moiré may occur. more likely to occur.

Recently, there is a method of performing gravure printing using halftone positive for planography or letterpress printing. In such a 2-method, moiré may occur between the net positive chip and the gravure screen. Traditional methods have been devised to prevent the occurrence of moiré. For example, a method is known in which a gravure screen is not formed from the light part to the halftone part. However, in this method, a negative chip is required when printing the gravure screen, and it is also necessary to register the net positive chip with the negative when printing it.

A method of using a grain screen instead of a gravure screen is also disclosed in US Pat. No. 2,096,794. However, this sand grain sufu-/ is usually 100
With a roughness of about t/1 nch, it has the disadvantage that it feels rough in practical use, and it also has the disadvantage that unevenness tends to occur because there is a large difference in the area of the orchid cells.

Further, a gravure screen for preventing moiré that may occur between a net positive chip and a gravure screen is disclosed in British Patent No. 974,884. It seems possible to prevent the occurrence of moiré by using the gravure screen disclosed herein, and it seems to be preferable because there is no big difference in the area of the 11 cells. . However, the butter/illusion of this screen: it consists of a repetition of a pattern in a certain unit.

The present invention aims to provide a new gravure screen that is completely different from the gravure screens described above and which prevents the occurrence of moire.

Generally, gravure screens are known as negative type and positive type.

A positive type gravure screen consists of continuous transparent line segments and an opaque area surrounded by the transparent line segments, and a negative type gravure screen consists of
It consists of a continuous opaque line segment and a transparent part that is overlapped by the opaque line segments.

The present invention can provide both such positive type and negative type gravure screens.

A gravure screen generally has a transparent part and an opaque part formed on a substrate such as a glass plate or a synthetic resin film. In the gravure screen of the present invention, the above-mentioned substrates are appropriately selected and used as the substrate.

As shown in Figure 1, the most common gravure screen used in the past consists of a large number of vertically transparent or opaque line segments (1) and a large number of horizontally transparent line segments (1). Alternatively, it has a pattern in which opaque line segments (2) intersect.

In the case of a positive type gravure screen, the vertical and horizontal line segments in Figure 1 are transparent, the cell portion (3) between them is opaque, and in the case of a negative type gravure screen, it is transparent. The relationship between opacity and opacity is reversed.

The gravure screen obtained according to the present invention does not have such a regular pattern but a completely irregular pattern.

That is, in the gravure screen 5 obtained according to the present invention, the points of the cell portion are made of irregular polygons, and the length of transparent or opaque straight lines forming these polygons is irregular within a predetermined range. The areas of the irregular polygons vary regularly and irregularly within a predetermined range, and polygons with different numbers of angles are included.

The gravure screen obtained according to the present invention can provide good printed matter without causing moiré.

The gravure screen of the present invention has a cell portion with a square pattern, or a cell portion with a triangular or hexagonal pattern [based on a pattern in which the shape of a solid polygon is irregularly changed]. ing.

The present invention attempts to manufacture the gravure screen as described above based on a group of polygonal patterns that are not regular polygons. The polygon pattern group that is not a regular polygon is often obtained by making a plurality of parallel line groups orthogonal or oblique. FIGS. 2 and 3 are examples of rectangular pattern groups obtained by orthogonally intersecting horizontal parallel line groups and vertical parallel line groups.

In the case of Fig. 2, the distances between the lines constituting the group of parallel lines in the horizontal direction are equal, and the distances between the lines constituting the parallel lines 71Y: in the vertical direction are equal by #I, but the distances between the lines in the horizontal direction are equal. Distance and vertical line distance are not equal.

In the case of FIG. 3, the distances between the lines constituting the group of parallel lines in the horizontal direction are not uniform, and the distances between the lines constituting the group of parallel lines in the vertical direction are also not uniform.

FIG. 4 is an example of a polygon pattern group in which two sets of parallel line groups are printed, and FIG. 5 is an example of a polygon pattern group in which three parallel line groups are printed orthogonally and diagonally.

As mentioned above, a pattern group that is not a regular polygon can be obtained by orthogonally or obliquely moving a plurality of parallel line groups, but a hexagonal pattern group can also be considered.According to the present invention, a gravure screen is It is also manufactured with seven patterns that are not regular polygons.

That is, the positional information of each intersection of each line segment constituting the polygonal pattern group as described above is recorded, and irregularities within a predetermined range are created around each of the intersections to create a pattern at each of the intersections. Determine and record the position of the corresponding new point, and connect the new points in correspondence with the line segments forming the polygon based on the position information of the new point to form a modified polygon pattern. Then, calculate the area of each of the modified polygons, and if the area exceeds a predetermined range, erase the line segment connecting the new points according to a predetermined format and/or erase the new points in a predetermined manner. Connect according to the pattern to form an irregular deformed polygon pattern in which the area of all deformed polygons is within a predetermined range, and the irregular deformed polygon putter/
A gravure screen is manufactured by using it as an original pattern/binding of transparent or opaque line segments of a gravure screen.

Hereinafter, the present invention will be explained in more detail a1 using as an example the case of a polygonal shape (butter/) in which two sets of parallel lines are orthogonally crossed.

U: In the case of patterns that are not regular polygons, such as the patterns shown in Figures 2 to 5, the distance between each intersection point is different in the horizontal and vertical directions, so the positions of the intersections are In the case of irregular displacement, it is preferable that the irregularity be different from that of a regular polygon.

For example, in the case of the pattern shown in Figure 2, the intervals between the groups of straight lines in the vertical direction are all the same distance (X), the intervals between the groups of straight lines in the horizontal direction are all the same distance (2), and the distance between X and Y The values of are different. In such a case, the irregularity of displacing the position of the intersection of each straight line in the @ pattern is made different in the horizontal direction and the vertical direction. That is, the position of each intersection is in the horizontal direction,
Displacement in the vertical direction is limited to, for example, within 30 degrees and 4 degrees, respectively.

Figure 6 shows the amount of displacement in the horizontal and vertical directions, respectively.
It is limited to within 10-2cm
2 0, +02, ±0,4, ±0.6, ±Q, 8, +1.0
Randomly generate a number, and convert this generated number to
A, n, C1...■2 each by the amount multiplied by Y
2 Displace the position of the intersection to obtain A/, n/, c/,・
This is an example of finding the position of ■' and connecting these points.

FIG. 7 shows an example of a pattern obtained by modifying the pattern of FIG. 2 in this manner.

In the case of the pattern shown in FIG. 3, the intervals between the straight lines in the vertical straight line group are also random, and the intervals between the straight lines in the horizontal straight line group are also random. In this case as well, it is sufficient to randomly set the amount of displacement within the limit of a displacement amount of half or less of the interval between each straight line, find the position after displacement, and connect the positions after displacement with a line segment.

FIG. 8 is an example of a pattern in which the position of each intersection point is displaced in this way.

As explained above, it is preferable to impose a certain limit on the amount of displacement at each intersection, and the limit is shown in the general example of FIG. 9 as follows.

The distance from the intersection point (E) to the adjacent straight line m is within the range of the rectangular figure obtained by connecting the points in FIG.

Therefore, it is equivalent to specifying arbitrary coordinates irregularly within the area as the displaced position.

-10~ Even in the case of other polygons, a deformed polygonal putter may be formed by irregularly displacing the polygons with appropriate restrictions.

As described above, an irregular pattern can be obtained, and this pattern can be used to print a gravure screen.However, in this irregular pattern, moiré can be prevented, but on the other hand, the cell part The area also changes irregularly.

The variation in the area of the cell portions gives the printed matter a rough feel. The reason for this is that when the gravure plate is etched, the etchant sufficiently penetrates into the small area of the cell part, so that the cells in that part are only etched shallowly. Therefore, the ink is not sufficiently transferred to the printed material in that area, giving the printed material a rough feel.

Furthermore, even if large cells and small cells have the same depth, the ink transfer rate during printing is smaller in the smaller cells, causing an accentuated roughness.

In the present invention, such inconveniences are eliminated.1- That is, after forming a modified polygon pattern as described above, the area of each modified polygon is determined. Any method may be used to find the area of this modified polygon, for example,
In the case of a deformed quadrilateral KLMN as shown in Figure 0, the respective coordinates are K (x+ + y+) and L (X2゜yz)
, M (x, ys), N (Xi, y4), the area S can be calculated using the following formula.

-'J2-Nx+ x41"ly+ ytl+Ix
t x+I”lyt yt y+l+l Xs −
X21・lyz -yt l -1-IX4-xs l
・Iy<ysll If the area of the irregular polygon thus extracted exceeds a predetermined range, for example, the area of the original regular polygon is larger than the predetermined range or larger than the predetermined range. If it is small, the irregular polygon division process or merging process is not performed.This division process and merging process illusion:,・
This refers to the work of connecting non-adjacent vertices of the irregular polygon and the work of erasing one side of the irregular polygon, respectively, and the selection of the vertices and the selection of the sides occur after the work is performed. The area of the new irregular polygon must be carried out under the condition that it does not exceed a predetermined range.

FIG. 11 is a drawing for explaining the situation in which area restrictions are applied to the group of irregularly deformed rectangles in FIG. The line segments drawn as thick lines indicate the line segments that will be newly connected through the division process.

FIG. 12 shows a pattern that has been subjected to operations for adding area restrictions in this manner.

As is clear from FIG. 7, even if the original rectangles are only transformed, the patterns are all quadrilaterals even after the transformation. In other words, the number of angles of the original polygon and the polygon after transformation are the same. This also applies to triangular and hexagonal patterns.

On the other hand, as is clear from FIG. 12, the deformed pattern after applying the area restriction includes polygons with various numbers of angles. The shapes of these polygons with various numbers of angles are completely irregular, and the areas of these polygons are within a predetermined range.

According to a gravure screen created using a ``Tsuna'' pattern as an original pattern, the roughness of the printed material is reduced by 1 to 100%.

As can be seen from FIG. 12, the irregularity of irregular polygons subjected to area restriction by the method of the present invention is improved. This is because, as shown in Figure 11, by removing the line segment indicated by the dotted line, a continuous line segment was divided, and a state in which polygons with different numbers of angles coexist was revealed. This is due to

In order to create a modified polygon pattern with area restrictions as described above, it is preferable to use a computer to create it in terms of efficiency, but it is also possible to manually create an enlarged pattern and reduce it. is also possible.

In the present invention, the modified polygonal pattern obtained by applying area restriction in this manner is used as an original pattern of transparent or opaque line segments of a gravure screen.

Various means can be used to obtain a gravure screen using the original pattern.

For example, an electronic dividing machine is used to calculate the deformed polygon pattern ~/, and the resulting data is used to control an automatic engraving machine and the like to scribe a transparent glass plate that has undergone the necessary processing. , it is possible to adopt a method of creating a gravure screen using a normal method.

Alternatively, the deformed polygonal pattern is subtracted using an electronic divider, etc., and the resulting data is used to control the exposure device to form an output on a photosensitive film, which can be used as a gravure screen. can do.

Alternatively, a drafting device is controlled based on the data of the calculation result to output and form a modified polygonal pattern on paper, etc., and this output pattern is formed on a transparent film or glass plate using photographic techniques or other means. It may also be used as a gravure screen.

In the present invention, the original pattern may be created with the same dimensions as the final product, but if line width and accuracy are taken into account, the original pattern may be enlarged to a certain extent and then photographed in a reduced size to be used as a gravure screen. .

If the memory capacity required to obtain a gravure screen of the required size becomes large and the processing time and other loads become too large, connections may be made by multiple exposure of the original pattern or the like. In this case, it is sufficient to move the intersection point of the connecting portion to a position where the connection can be made properly.

In the present invention, if the line segments of the modified polygonal putter are made transparent and the other parts are made opaque, it becomes a positive type gravure screen, and vice versa, it becomes a negative type gravure screen. . Which one to obtain may be selected as appropriate.

The gravure screen of the present invention is obtained as described above, and the points of the opaque or transparent cell portions include polygons with different numbers of angles, and the transparent or The length of the opaque line segment varies irregularly within a predetermined range.

The area of the cell portion of the folded gravure screen of the present invention varies irregularly within a predetermined range.

The gravure screen of the present invention is not limited to starting from a rectangular cell shape, but may also be triangular, and can be made in the same way as for a rectangular cell shape. Furthermore, in the case of a hexagonal cell shape, the same applies! ! ! ! It can also be crushed.

The gravure screen of the present invention has transparent or opaque line segments that change irregularly, so it does not cause moiré, and the area of the cell part is within a certain range, so it is compared to a grained screen. This has the effect that unevenness and roughness are less likely to occur.

Furthermore, according to the present invention, a gravure screen with a smaller rate of variation in cell area can be used, compared to a putter in which the positions of the intersections of regular polygons as shown in FIG. 7 are simply changed. As a result, ink transferability in the cells formed on the gravure cylinder 17- is improved compared to a gravure screen obtained using a pattern as shown in FIG. This has the effect of eliminating roughness.

Furthermore, according to the present invention, a gravure screen with improved pattern irregularity compared to the gravure screen obtained using the pattern shown in FIG. is obtained,
The moiré prevention effect is further improved, contributing to the provision of printed matter with less sharpness and roughness.

′! Also, by using the gravure screen putter of the present invention, you can use the gravure screen putter! lI
! J construction is possible. When manufacturing a contact screen, the gravure screen pattern consisting of transparent line segments is double-exposed to a photosensitive material, so that the gravure screen pattern consisting of opaque line segments and the desired gravure screen pattern are formed. A contact screen for gravure that also has a density gradient corresponding to the halftone dot shape.
/ can be manufactured. Said gravure contact screen υ-/
If halftone positive photography is carried out using 18-, a halftone dot pattern divided by transparent and irregular line segments is formed on the photosensitive material through one exposure process.

Similarly, in the case of a negative screen, D1: When manufacturing a contact screen, by using the gravure screen pattern composed of opaque line segments as a mask, a gravure screen/butter/ made of transparent line segments and a desired net are formed. A contact screen for gravure that also has a concentration gradient corresponding to the dot shape can be manufactured.

Note that, so far, the case of a gravure screen has been mainly described, but the present invention can also be applied to a letterpress or lithographic screen in addition to a gravure screen.

[Brief explanation of drawings]

FIG. 1 is an explanation showing the pattern of the gravure screen used in the present invention, FIGS.
The figure shows the intersection of the patterns in Figure 2 and Figure 3, respectively.
An example of a pattern obtained by irregularly deforming the pattern shown in the figure is shown, and FIG.
Figure 0 is an IJJ diagram explaining a modified quadrilateral, Figure 11 is a diagram explaining the situation in which area restrictions are applied to the irregular modified polygon pattern in Figure 7, and Figure 12 is a pattern with area restrictions applied. FIG. (1)...Vertical transparent or opaque line segment (2)
...4' Transparent or opaque line segment in r/j direction (3
)... Cell portion patent applicant Toppan Printing Co., Ltd. Figure 1 1 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 31 Figure 6 Figure 8 Figure 9 Figure 10 M (X3.y3) Figure 1j

Claims (1)

[Claims] (1) Record the positional information of each intersection of each line segment forming a polygonal pattern group that is not a regular polygon, and create irregularities within a predetermined range around each of the intersections so that each of the intersections determine and record the position of a new point corresponding to the new point, and form a modified polygon pattern by connecting the new point in correspondence with the line segment forming the polygon based on the position information of the new point. Then, the area of each of the modified polygons is determined, and if the area exceeds a predetermined range, the line segment connecting the new points is erased according to a predetermined format and/or the new point is Connect according to the pattern to form an irregular modified polygon pattern in which the area of all modified polygons is within a predetermined range, and use the irregular modified polygon pattern as the original pattern of transparent or opaque line segments of the screen. A method for manufacturing a screen, characterized in that it is used as a screen.