JPH0519478B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing plate installed in an offset duplex printing machine.

In recent years, in order to automatically adjust the amount of ink supplied from the ink fountain of an offset printing press, ink adjustment of the ink fountain has been developed by optically scanning the printing plates for each color attached to the printing press before printing starts. Measure the area ratio of the printed area of the printing plate for each width of the key, input this measurement data into the ink adjustment key remote control device of the printing machine, activate the ink adjustment key, and automatically adjust the ink supply amount. A system has been developed to do so.

However, when measuring the area ratio of the printed area of an offset printing plate, if it is a four-color printing machine,
It is necessary to measure four printing plates: red plate, eye plate, and black plate, and even if it is a 4-color printing machine, if it is an offset winding rotary printing machine, the front and back sides of the printing paper will be printed at the same time. Since 8 printing plates will be mounted, it is necessary to measure 8 printing plates.

Also, since the area ratio measuring device measures these four or eight printing plates as a set, it is difficult to determine the printing color of the printing plate to be measured or whether it is printing on the front or back of the printing paper. Currently, each printing plate is measured by inputting it into a measuring device one by one from a keyboard or the like before measurement, or printing plates of each color are measured in a predetermined order with a measuring device.

However, specifying the printing surface of a printing plate using a keyboard or the like when measuring area ratio is surprisingly troublesome, and since there is not much visual difference between each printing plate, it is easy to misidentify the printing plate, so it is difficult for the operator to There is a risk of incorrectly specifying the printing surface of the printing plate, and there is a risk that each printing plate and the print area ratio, which is the output data, will be different. On the other hand, in the case of a measuring device that measures printing plates in a predetermined order, for example, if they are set on the printing plate stand in the wrong order, the measurement will continue, and in this case, each printing plate will also be This results in a discrepancy between the output data and the drawing area ratio.

Therefore, the object of the present invention is to measure the area ratio of the printed area of an offset printing plate without worrying about the order of measurements, etc., and to be able to measure the area ratio even if the measurements are run on a measuring device in any order. To provide an offset printing plate for a double-sided printing machine in which output data does not differ depending on whether the printing plate prints on the front or back side of printing paper.

The present invention, which has been made to achieve such an object, is a printing plate that is attached to an offset printing machine that prints on both sides of supplied printing paper, and the printing plate is used to measure the area ratio of the printed area. A mark is provided outside the effective picture area of the printing plate to indicate which side, front or back, of the printing paper the printing plate is used for printing on, and this printing surface designation mark is set according to a certain standard. This is an offset printing plate that is expressed by the presence of an image area at a position a predetermined distance away from a point.

The present invention will be explained in detail below based on embodiments of the drawings. FIG. 1 is a plan view of an offset printing plate according to the present invention, FIG. 2 is an enlarged explanatory view of the main part, and FIG. 3 is an enlarged explanatory view of the main part of another embodiment of the present invention. .

As shown in Figure 1, the image to be printed on the offset printing plate (hereinafter simply referred to as the printing plate) P generally has a border-colored image area (low reflectance area) and the exposed aluminum base, giving it a silver color. The effective picture area 1 is surrounded by a dashed-dotted line 3, and the area outside the dashed-dotted line 3 is a blank area 2 where the aluminum substrate is exposed.

In measuring the area ratio of the image area of the printing plate P, for example, the entire surface of the printing plate P is scanned with a laser beam, the reflected light is received by a photoelectric conversion element such as a photoprinter, and an A/ Perform D conversion,
Furthermore, this data signal is made into a data signal for each unit pixel by a pulse signal supplied separately.

At this time, the image area is a low reflectance area and the non-image area is a high reflectance area, so the magnitude of the signal is determined by the ratio of the image area and non-image area for each unit pixel. Also, during the scanning process, the 100% image area (solid area) of the calibration mark 11 is
By detecting 12 and 0% drawing area 13,
It is possible to measure the magnitude of the electrical signal in the 100% image area 12 and the 0% image area 13, and use this as a reference signal to compare and calculate the data signal for each pixel to determine the image area for each unit pixel. The area ratio can be obtained. Although the 0% image area 13 is indicated by a dotted line, it is actually made of the same aluminum material as the other margin areas.

In measuring the area ratio of an image area in this manner, the unit pixel is determined by a pulse emitted from a pulse generator or the like in order to calculate area ratio data for each unit pixel. Therefore, by counting the pulses emitted from the start of scanning, it is possible to determine which position on the printing plate has been determined. For example, in FIG. Assuming that scanning (feeding) is performed in the horizontal direction, by inputting the plate size in advance, it is possible to know at what pulse number the point A at the lower end of the center line 4 is irradiated by the laser beam. In this embodiment, marks as described below are provided based on this point A.

That is, as shown in the drawing, an area 12 indicating the 100% drawing area of the calibration mark 11 is provided on the left side of this center line, and an area 1 indicating the 0% drawing area is provided on the left side of this center line.
3 on the right side. This allows you to know how many pulses before or after reference point A is the 100% print area or 0% print area, and the data corresponding to that number of pulses can be imported as calibration data. .

Further, as shown in an enlarged view in FIG. 2, an area is provided at a certain distance from the center line 4 for marking a mark M specifying the printing color of the printing plate.

That is, area group 14 corresponds to a printing plate mounted to print on the front side in an offset winding rotary printing press, and area group 15 corresponds to a printing plate installed to print on the back side. . Areas 16, 17, 18, 19, and Area 2
0, 21, 22, and 23 are those on which printing color designation marks M are formed for each front and back, for example, a key plate,
If it corresponds to the red plate, eye plate, and black plate, and if this mark M is formed in area 16, it is understood that this printing plate prints on the front side of the printing paper and is the clear plate, and , if the mark M is applied to the area 21, it is understood that this printing plate is printed on the back side of the printing paper and is a red plate. In this way, in this embodiment, one mark M serves both as a print surface designation mark that designates which side of the printing paper is to be printed, and a print color designation mark that designates the print color. .
Note that the mark M as described above is expressed by forming an image portion in the area. Since the distance of each of these regions from the center line is determined, it is known which pulse number the region is located from the reference point A. Therefore, in the process of scanning the laser beam on the printing plate, each region If the printing area is measured in the area corresponding to the number of pulses corresponding to It can be recognized by the arithmetic processing unit in the measuring device, and accurate image area ratio data can be output.

In another embodiment of the present invention, as shown in an enlarged view in FIG. 3, a region 3 in which a mark M indicating the color of the printing plate is formed.
Area group 31 consisting of 3, 34, 35, 36 and areas 37, 3 where marks M are formed indicating whether the printing plate is used to print on the front or back of the printing paper.
It is divided into a region group 32 including 8.

Areas 33, 34, 35, and 36 indicate, for example, a clear version, a red version, an eye version, and a black version, respectively.
Designated mark M consisting of a drawing area in these areas
, it is recognized that this printing plate has the printing color indicated by that area. Also, area 3
7 and 38 are areas indicating, for example, those to be printed on the front side of the printing paper, and those to be printed on the back side, respectively. If a designation mark M consisting of a drawing area is formed in the area 37, this printing plate will be printed on the printing paper. The printing plate is for printing on the front side, and conversely, if the designation mark M is present in the area 38, it is recognized that this printing plate is for printing on the back side of the printing paper.

These areas are each located at a predetermined distance from the reference point A, as in the previous embodiment, so that the scanning spot of the laser beam is always placed on those areas at the time of the number of pulses corresponding to those distances. Therefore, each pulse number is stored in advance in the measuring device, and by detecting the presence or absence of the image area at the time of the pulse number, the printing color and printing surface of the printing plate can be determined. can be recognized.

In addition, in the above embodiment, a printing plate that is attached to a printing machine that simultaneously prints on the front and back sides of the printing paper was described, but in order to be compatible with a printing machine that prints only one side of the printing paper, it is necessary to print on the front side of the printing paper. It is sufficient to arrange in advance to mark the item as such.

In addition, in the above embodiment, four colors consisting of the three primary colors and ink are used.
We have described the case of basic multicolor printing, but
To accommodate printing machines that add some special colors to the basic four colors, such as five-color printing machines and six-color printing machines, it is sufficient to separately provide an area that shows the special colors.

Furthermore, in the above embodiment, an example for indicating the printing color and printing surface of the printing plate was shown, but the printing color and printing surface may be distinguished by a combination of mark positions such as a bar code. It goes without saying that the marks may be distinguished by the size of the marks, or by placing marks in two stages, upper and lower, or by inserting other marks.

As described in detail above, according to the present invention, in measuring the area ratio of the image area of a printing plate, the printing plates are arranged in a predetermined measurement order, and the front and back sides of the printing paper of the printing plate are simultaneously measured. There is no need to specify which side to print using a keyboard, etc.; by randomly selecting a measuring device from among a set of printing plates, either the front or back side of the printing paper can be printed from the printing plate itself. Therefore, it is possible to perform measurements accurately, and it also leads to a significant improvement in the efficiency of measurement work.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention.
The figure is a plan view of an offset printing plate according to the present invention.
FIG. 2 is an enlarged explanatory view of the main part of FIG. 1, and FIG. 3 is an enlarged explanatory view of the main part of another embodiment of the present invention. 1... Effective picture area, 2... Margin, 4... Center line, 14, 15, 31, 32... Area group, 1
6, 17, 18, 19, 20, 21, 22, 2
3, 33, 34, 35, 36, 37, 38...Area, M...Specification mark, P...Offset printing plate.

Claims (1)

[Claims] 1 A printing plate attached to an offset printing machine that prints on both sides of the printing paper supplied, and the printing plate is used for measuring the area ratio of the printed area, and the effective A mark is provided outside the picture area to indicate whether the printing plate is used to print on either the front or back side of the printing paper, and this printing surface designation mark indicates the presence of a printed area at a position a predetermined distance from a certain reference point. An offset printing version characterized by being expressed by.