JPS6150308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a large-sized original plate for producing a printing plate.

In the plate-making process, for example, the offset plate-making process, a multicolor original is color-separated using a scanner to obtain continuous tone color separation negative or positive film, which is then halftone-photographed using a plate-making camera to produce halftone positives or halftone negatives for each color. Alternatively, a multicolor original is subjected to direct halftone color separation using a direct scanner to directly obtain halftone positives or halftone negatives for each color. Then, a printing plate is produced using the mesh positive or mesh negative thus obtained.

The dimensions of these net positives or net negatives must be equal to the finished dimensions of the print. Therefore, if the finished size of the printed matter is large, the size of the net positive or net negative must be correspondingly large. However, just because the finished size of the printed matter is large, there is a limit to the size of the net positive or negative. That is,
There are limits to the output size of the scanner used in the process of obtaining net positives or net negatives by the method described above, the size of the prepress camera, and the size of the screen for printing (for example, the maximum size of the prepress camera is 1400 mm x 1400 mm).
(about 810 mm x 610 mm (maximum 810 mm x 610 mm) for a screen for net photography with 150 lines per inch), and it is not possible to produce net positives or negatives with sizes exceeding this limit.

Due to these circumstances, conventional techniques have been to divide the plate and make it, print it and then paste it together, divide the plate and make it, then cut the plate with a cutter according to trimming and paste it on the Lumirror base, or make the plate in small size and optically scan it with a camera. Large-sized prints are obtained by methods such as enlarging the image. However, the first method described above has the disadvantage that seams are formed in the paper of the printed matter, the second method has the disadvantage that the printing effect is not good because streaks occur on the printing plate at the bonded part, and the third method Each of these methods has the disadvantages that the tone becomes hard, it is not possible to obtain a halftone plate with a very fine number of lines, and although the screen size can be small, the size of the plate-making camera needs to be up to the finished size. Neither method can be said to be satisfactory.

In view of the above problems, the present invention aims to provide a method for producing a large-sized original plate that makes it possible to obtain printed matter superior to the large-sized printed matter obtained by the above-mentioned known methods.

Next, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a continuous-tone positive original document having a pattern 2. In FIG. From this manuscript 1, a net original plate 3a is produced as a partial original plate consisting of a net negative or a net positive having a part 2a of the image enlarged to the finished dimensions of the pattern of the printed matter, and similarly A halftone original plate 3b as a partial original plate made of a halftone negative or halftone positive having the other part 2b of the picture enlarged to the extent that the pattern is enlarged is produced.
The patterns 2a and 2b of these Amihara plates 3a and 3b are
One picture 2 is not completely divided, but is divided in a partially overlapping state. These halftone plates 3a and 3b are produced by color separation and halftone photography through a screen using a plate-making camera, or direct halftone color separation using a direct scanner, as in the above-mentioned known case. can be done. Although FIG. 1 representatively shows only one-color halftone original obtained by color separation, it goes without saying that FIG. 1 also includes the case of monochrome printing.

As described above, in the present invention, the same halftone plate manufacturing method as in the conventional case is adopted, but the pattern 2 of the manuscript is
Since the halftone plate is produced in two parts 2a and 2b (in some cases three or more parts), each picture part 2a and 2b itself has a halftone plate having one picture 2 at the same magnification. The size is smaller than when making it. In other words, even if it is dimensionally impossible to make a halftone block that includes all of the pattern 2 at a certain enlargement ratio, it is possible to make a halftone block for each of the picture parts 2a and 2b because the picture is divided. It is.

Amihara plates 3a and 3b obtained as above
are then pasted onto pasting sheets 4a and 4b, and these pasting sheets 4a and 4b are then subjected to registration means 5 in a state where both pattern portions 2a and 2b completely overlap each other as a continuous pattern. be done. Most preferably, the registration means 5 are constituted by registration holes.

Meanwhile, mask plates 6a and 6b are prepared. The mask plate 6a is provided with a light transmitting part 7a and a light shielding part 8a, and there is a boundary line 9a between them.
The light transmitting portion 7a is provided at a position that covers most of the pattern 2a of the screen printing plate 3a pasted onto the pasting sheet 4a. That is, the light transmitting portion 7a is positioned such that its boundary line 9a coincides with the dividing line A that divides most of the part 2a of the pattern and most of the other part 2b of the pattern 2 at an arbitrary position of the pattern 2. The part 2 of the picture that is pressed and to the left of the dividing line A
It is designed to correspond to a. Therefore, the light shielding portion 8a covers the portion of the picture portion 2a other than the portion on the left side of the dividing line A. The above-mentioned positional relationship between the mask plate 6a and the pattern portion 2a of the pasting sheet 4a is as follows.
This can be achieved by providing registration means 10 similar to that of the pasting sheet 4a.

The other mask plate 6b also has a configuration similar to that of the mask plate 6a. However, in the case of the mask plate 6b, the positions of the light transmitting part 7b and the light shielding part 8b with respect to the boundary line 9b are reversed, and the light transmitting part 7b is located at the pattern part 2b of the pasting sheet 4b.
Therefore, the light shielding part 8b is designed to cover all parts other than the part of the picture part 2b to the right of the dividing line A.

The mask plate 6a prepared so as to have the above-mentioned relationship is stacked on the pasting sheet 4a in a registered state using the registration means 5 and 10, and is then overlapped in the process shown in FIG. be brought to the final state.

As shown on the left side of FIG. 2, the screen original plate 3a of the laminated sheet 4a stacked in this manner is printed onto a photosensitive material (raw film) 11 in a printer while being covered by a mask plate 6a. . That is, the mask plate 6a is placed on the glass surface G of the printer.
Screen printing plate 3a on pasting sheet 4a, photosensitive material 11
They are placed in close contact in this order and exposed to light in the direction indicated by L. In FIG. 2, 3a1 represents the emulsion surface of the halftone plate 3a, and 11a represents the emulsion surface of the light-sensitive material 11.

Through the above-described printing process, the pattern portion 2a of the screen original plate 3a on the left side of the dividing line A is printed onto the photosensitive material 11.

After this baking process is completed, the other mask plate 6b
is the registration means 5, 10 for the pasting sheet 4b.
The screen printing plates 3b of the pasting sheets 4b stacked in this way are stacked in registration using
As shown on the right side of FIG. 2, the same photosensitive material 11 that was previously subjected to the printing process is printed while being covered by the mask plate 6b. As a result, the pattern portion 2b of the halftone plate 3b on the right side of the dividing line A is printed onto the photosensitive material 11.

As a result of printing the pattern 2 on each side of the dividing line A as described above, the photosensitive material 11
A pattern 2 as shown in FIG. 3 appears as a result of development, and an original plate 11' is obtained. Note that it is clear that the above-mentioned two baking operations may be performed in reverse order. In addition, although the above description has been made assuming that the pattern is divided into two parts by a single dividing line A and printed, the same principle can be used to print the pattern even if the pattern is divided into three or more parts, as shown in Fig. 3. An original plate 11' as shown in FIG. 1 can be obtained. The larger the number of divisions, the larger the original plate can be obtained. Note that the dividing line does not necessarily have to be a straight line and can have any shape. In this case, as a matter of course, the shapes of the light shielding portion and the light transmitting portion of the mask plate change.

According to the present invention described above, it is possible to reliably maintain the precision of the mask, etc., so that if normal processing is performed, there will be no visible traces of joining of the patterns bordering on the dividing line. Furthermore, in the present invention,
Although the printer used for printing to obtain the original plate is required to have dimensions corresponding to the original plate, there is no need for extra large-sized equipment other than the printer.
As for the printer, by using a bright room type film, the printing frame of the printing plate can be used. Furthermore, in the present invention, the reproduction of tone is not inferior to that in the case of a small size, and in the case of a screen printing plate, it is possible to make a plate with an arbitrary number of screen lines. Note that in the case of multicolor printing, the effects of the present invention are further improved by making the position of the dividing line different for each color.

Although the above description has been made mainly for offset printing, the principles of the present invention can also be applied to letterpress printing plates, gravure printing plates, and continuous tone printing plates for gravure printing.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the process before baking in the method for producing a printing original plate according to the present invention, FIG. 2 is a diagram showing the baking process, and FIG. 3 is a diagram showing the finally obtained original plate. 1...Manuscript, 2...Picture of the manuscript, 2a, 2b...
...Part of the picture, 3a, 3b... Partial original version (mesh original version), 4a, 4b... Paste sheet, 5, 10...
...registration means, 6a, 6b...mask version, 7
a, 7b... Light transmitting part, 8a, 8b... Light shielding part, 9a, 9b... Boundary line, 11... Photosensitive material,
11'...Original plate, A...Parting line, G...Glass,
L...Exposure.

Claims (1)

[Scope of Claims] 1. An enlarged partial original having a picture corresponding to a part of the picture of the manuscript, and corresponding to other parts of the picture of the manuscript, including a part that partially overlaps with the part of the picture of the manuscript. preparing at least two similarly enlarged partial masters having a pattern of
Each of these partial originals is pasted onto a pasting sheet, and the registration means is used to perform registration so that the patterns of the one part and the other part of the partial masters of these pasting sheets overlap as a completely continuous pattern. Registration is applied to these pasted sheets so that they have a light-shielding part on one side of an arbitrary dividing line that divides a continuous pattern, covering a pattern part other than the part of the pattern on the partial original of the pasted sheet. A mask plate on which the above-mentioned partial pattern has been applied is prepared, and a partial original pasted sheet having the partial picture is superimposed behind the mask plate using an alignment means, and the partial master of this pasted sheet is placed on a photosensitive material. Another mask plate is printed on the other side of the dividing line and is provided with a registration means so as to have a light shielding portion that covers a pattern portion other than the pattern of the other portion of the partial original plate of the other pasting sheet, which is on the other side of the dividing line. Prepare and behind this other mask version,
The partial master pasted sheets having the designs of the other parts are overlapped using a registration means, and the partial master of this pasted sheet is printed on the same photosensitive material that has been printed as described above. A method for producing a large-sized printing original plate, which comprises obtaining an original plate having a synthetic pattern from photosensitive materials that have been subjected to overlapping printing as described above. 2 Claim 1 in which the partial original is a halftone positive
The method described in section. 3 Claim 1 in which the partial original is a net negative
The method described in section. 4. The method according to any one of claims 1 to 3, wherein the registration means is a registration hole. 5. The method according to claim 1, wherein the partial original is a continuous tone film.