The form of the printing element for offset printing

 

The invention relates to the form of the printing element of the set separated from each other along the perimeter jumpers printing elements of the printing unit for offset printing, in particular a rotary offset printing, and the corresponding printing element has a geometric polygonal shape. The printing element to simulate the density of the tones on the material for sealing contains many distributed over the surface of the printed dot printing elements, each printing element is limited only by the S-shaped lines and lines make all the vertices of the printing element angle90. Thus, we achieve a new form of printing elements, through which possible would have been even sharper pictures and an even more subtle and gentle nature shades. 13 C. p. F.-ly, 5 Il.

The invention relates to the form of the printing element of the set separated from each other along the perimeter jumpers printing elements of the printing unit for offset printing, in particular a rotary offset printing, and the corresponding printing element has a geometric polygonal shape.

Since HRP raster old, retractaway lithography or at least to approach it as close as possible. With the development of photolithography has become increasingly clear that technically traditional rasters is possible, however, to achieve a relatively high print quality, but does not simulate the old lithographic prints. Photomechanical rasters, such as, for example, raster “Gradara or purple raster, very well suited for newly developed photolithography, as well as for the technique of reproduction. These types of rasters always inherent, however, certain technical disadvantages, such as the cliffs of the raster, the formation of moire, the formation of secondary moiré and education outlets. There is still a desire to create a autolithography, i.e., lithographic print, no raster only with the grain size of the surface of the stone as a printing element for offset printing.

Therefore, first of all, in General, faced with the task of making berastagi lithographs. First was proposed to use as the base color grain slides to selekcionirovat this grain through separations and be used as a printing element. The attempt failed due to the imperfection of industrial materials. Partial travie programs are subject to processing controlled by a random number generator, the problem arises that the smaller the resolution of the selected partitions, the more complicated the calculation of the corresponding gradation curve. From this perspective, this view of the raster, such as raster "Cristall", raster Diamond-Screen or raster Harleqir-HD-Screen" unsuitable for newspaper rotary presses.

Had to go back to a traditional raster technique of offset printing. In rotary offset printing printing form pull on the cylinder. The cylinder communicates with fitted rubber cloth extra cylinder, which, in turn, communicates with the cylinder back pressure, which passes through the printed paper. Print designated printing plates are made so that they repel water and absorb the greasy printing ink. Napechatala places are made so that they absorb the water and repel the greasy ink. During printing moisturize first, all the printed form, and water absorb only napechatala, the water-absorbing seats. Partially wet, thus, the printing form can then flow past the inking rollers that transport fatty paint on a non-humid place a printed form. The impression is then offset cylinder, and since it is on the printed paper.

Color space of the print Rassegna jumpers. Jumpers do not paint over. More than the total area of the jumpers at one point of the image, the lighter it seems this image point. The proportion of the shaded surface in the General area of the point of the image determines the gray tone, the density of the halftone dot image and usually indicated in percent.

Through a screen with many distributed thereon printing elements is possible by varying the magnitude of printing elements to simulate different halftone density. Known to perform printing elements in the form of squares, round surfaces, elliptical or other geometric surfaces. The sharpness of the outlines of the images could not fully satisfy when technically possible subtleties known forms of printing elements. The reason for this is that, while the average value of printing elements, i.e., when the average density of the tones of this image, there is a closure point, so that the sharpness of the contours and character of shades imprint unsatisfactory. The desired form of printing elements of the closure of the points should lie as far back into the depths, and a new form of printing elements should have the opportunity of perfect control through graded to the staggered, imaginary raster cells is one pachatusan element, so that when standing on a raster cells of arbitrary tone for all points of the bounding lines of the printing element, respectively, the shortest distance between the printing element at least approximately the same. While the print element must have mainly rabidou surface, the boundary lines of which are in the shape of an arc so that they form two diagonally opposite acute angles and two diagonally opposite each other round or obtuse angle. Due to this, the printing element has the shape of a flag.

This form of printing elements and its location in the raster have the advantage that theoretically closing points only occurs when the density of the halftone 100%. Although this form of printing elements has been developed especially for four-color printing, the lack of color images is still the formation of moire. This phenomenon can be prevented only if the printing elements for other colors, such as purple, blue or yellow, deployed relatively normal location when cerit the task of developing a new form of printing elements, which possible would have been even sharper pictures and an even more subtle and gentle nature shades, in particular, in order to avoid the generation of moire in the multi-color prints using only the same form of the printing element.

Based on experience with a printing element according to EP-A-0825490 as task provided that the corresponding printing element is limited only by the S-shaped lines and lines in all the tops of the printing element enclose an angle90. It is particularly expedient, if the printing element is not limited to only three, but better than four lines, because then there is a similarity propellerman configuration with smoothly curved S-shaped lines. Thus, it was found clearly defined geometric shape of the printing element.

This configuration of the printing element has the special advantage that the reflection of the propeller across the axis through the center and turning point between the opposing lines of depressions and elevations obtained the same value, the same form printing element. If reflected printing elements paint over another color, preferably when clenia moire, that is a significant advantage for four-color printing. When using this profilirovannogo of the printing element is not required from plagiarizing of the printing element of the spread of the printing element in order to avoid moiré pattern that can easily be installed through existing programs. This printing element is applicable for frequencies in the range 152-304 lines per inch.

Of course, the printing element is applicable without problems for four-color printing without reflection. 3 this case, in order to avoid moiré pattern printing element, as is known, should be deployed around the middle axis.

In order that the impression could have different degrees of brightness, i.e., changing the density of the colors, the printing elements should be separated from adjacent printing element surface that is not painted. These (white) surface at the location according to the application are in the form of lines, always the same width, namely in such a way that are next to each other, the printing elements of the raster - without location in a checkerboard pattern - match each other so that when anyone, including changing the tone of the distance from both neighboring sides of sledujuwij neighboring printing elements only when the density of the halftone about 100%. The consequence of this arrangement are mild differences in brightness and optimum sharpness of the outlines of the images obtained with this printing element.

This printing element, it is preferable to use, therefore, especially for color reproduction in a newspaper, role or sheet offset printing.

The form of the printing element according to the invention is depicted as an example in the drawing, which are:

- Fig.1: schematically the section of rollers known offset presses;

- Fig.2: in a strong increase in the top view individual propellerbuy printing element;

- Fig.3: printing element according to Fig.2 together with reflection around the axis x-X passing through the center of the printing element;

- Fig.4: in a slightly smaller increase certain number located next to each other preparirovannyh printing elements with the same density tone;

- Fig.5: also strong, however, in comparison with Fig.2 or 3 smaller increase a certain number of different sizes of printing elements, i.e., with changing density tone.

Offset machine according to Fig.1 operates with the plate cylinder 1 on which the tensioned printing plate 2. The plate cylinder 1 communicates, on the one hand, with the offset of the cylinder the other hand, with dye 6 and hydrating 7 devices. The transfer of printing ink 60 on the printed form 2 coloring apparatus 6 is performed through a certain number of pinch rollers 8. The water transfer 70 moisturizing device 7 is performed through a certain number of additional conveying rollers 9. All of the rollers or cylinders are rotated towards each other, as is partially indicated by the arrows.

Dampening unit 7 transfers the water to 70 napechataem places 10 of the printing form 2, while the print space 11 of the printing form 2 remain free from water. Wet place 10 repel printing ink 60 in the bridge 12 of the seal adjacent pinch rollers 8, while the print space 11 absorb the printing ink. Printing ink then transferred from the printing plate 2 on the offset cylinder 3 and forms there a coloring designated 11', finally presses the material 4 for sealing.

Print space 11 or coloring designated 11' are printing elements according to Fig.2 and 3. The latter is very small and not visible to the naked eye. In Fig.2 shows a strong increase of such printing element propellerman configuration according to the invention. The propeller has four S-shaped line 15 sides of equal length. Each is s or in the other direction starts increasing line 15" rise and ends with increasing line 15' depression. If all the S-shaped line sides of equal length, then the vertices, where the ending line elevation is joined with the beginning line of the trench, is formed angle 90.

With this configuration, the printing element 17 mirror has the same shape, but flat reflective element, which overlap with the base color has only rounded tops. Condition is a mirror reflection of the printing element across the axis x-X through the center and turning points between opposing S-shaped lines of the printing element. In Fig.3 shows such reflected printed item 17', which here is of the same value. In practice, depending on the desired composite color both converging printing element different colors can have different size. It is only important that when the same configuration of the printing elements and, thereby, continuing program for the manufacture of printing elements part of the printing element was printed with its own color without mixing, which prevents the occurrence of moire. Now if the necessary vertices of the printing element after flipping always rounded, the occurrence of moire is prevented without it the th elements are located directly next to each other so the distances between each two sides 15 of each neighboring printing elements is constant. Napechatala jumper 18 is always the same width. This is to prevent clamping points already at densities tones below 100%. Profilirovannogo print item regardless of its location in a checkerboard pattern on the surface of the printing point, never happens clamping points except when special printing point must be strictly black.

In addition, you should still refer to Fig.5, where propelleronline printing elements depicted unchanged, but on the surface Fig.5 or the printing point of the corresponding distances between the printing elements, i.e., jumpers 18, change in width. Thus, it also changes the density of the tone. Printed dot becomes to the bottom edge lighter. The expansion of the jumper, as seen above, can be smooth or a large percentage jumps, as seen below. Percent jump more only in the lower part of the image so that it in this resolution is noticeable stronger.

Claims

1. The printing element to simulate the density of the tones on Klimentov, characterized in that each printing element (17, 17') is limited only by the S-shaped lines (15) and lines make all the vertices of the printing element angle90.

2. Item under item 1, characterized in that the printing element (17, 17') has at least three lines (15) of the parties.

3. Element according to one of the preceding paragraphs, characterized in that each line (15) party starts at the top of the descending line (15') depression and ends with a descending line (15") of elevation or, on the contrary, starts increasing line (15") elevation and ends increasing line (15') of the hollow.

4. Element according to one of the preceding paragraphs, characterized in that all the lines of the sides of the printing element of the same length.

5. Element according to one of the preceding paragraphs, characterized in that the printing element is limited to four lines of the parties.

6. Item under item 5, wherein the printing element has the shape of a four-bladed propeller with blades of the same shape.

7. Element, in particular according to one of the preceding paragraphs, characterized in that when you mirror the printing element (17') across the axis (x-X) through the center and turning points between the opposing sides, the element is provided on p. 7, characterized in that in the process of printing multiple colors (four-color printing) mirrored form filled in respectively different color.

9. Item under item 8 with four-color printing and the colors black, Magenta, cyan and yellow, characterized in that complemented the mirror image printing element is formed by both printing elements with the color blue, and yellow, and on the other hand, with the color purple and black.

10. Item under item 8 with four-color printing and the colors black, Magenta, cyan and yellow, characterized in that complemented the mirror image printing element is formed by both printing elements with the color blue, and purple, and on the other hand, with the color yellow, and black.

11. Item under item 8 with four-color printing and the colors black, Magenta, cyan and yellow, characterized in that complemented the mirror image printing element is formed by both printing elements with the color blue and black, and on the other hand, with the color Magenta, and yellow.

12. Element according to one of the preceding paragraphs, characterized in that the printing element is limited to six lines of the parties and several printing elements of the printing dots are propell is routed next to each other printing elements of the printing element without location in a checkerboard pattern correspond to each other so what, if any, and under varying tone spacing (jumpers 18) from the two adjacent S-shaped lines of the parties before the next printing element is constant along the length of the S-shaped lines of hand.

14. Element according to one of the preceding paragraphs, characterized in that the four lines of the sides correspond to the following formulas: formulas apply to a single surface with dimensions x[-E;E] and[-E;E], with E[0; +], the zero point (0; 0) is the center of a single surface, for all radii ritrue i{1; 2; 3; 4; 5; 6; 7; 8}, r1=r2=r3=r4=r5=r6=r7=r8, ri[E/2; +], for a point (x1; y1) is true,1=E/2, for a point (x2; y2) true x2=E/2,for points (x3;3) true x3=-E/2,for points (x4;4) is true,4=E/2, for a point (x5; y5) is true, y5=-E/2, for a point (x6;6) true x6=-/.gif">for points (x8; y8) is true, y8=-E/2, the point (xi;i) are the center of the corresponding radius rifor all points (xi;i) true:

xi[;+], yi[;+].

 

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