Pre-inking and ink control technology based on CIP3/CIP4 standard
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CIP3 means computer integrated prepress, printing, postpress, prepress equipment (such as computers, scanners, digital cameras, imagesetters, platesetters, digital proofers, etc.) with presses and paper cutters and folding Machines are connected through network, floppy disk, smart card or manual input data, replacing the original experience with data, and managing the printing process with data, so that the machine realizes data and standardized management under normal linearization standards. High quality, high yield and low cost. CIP4 is based on CIP3 and adds a lot of more complete information collection, tracking, analysis, and even special instructions on the instructions, such as ink printing Lab value requirements, printing different versions of the number of instructions, etc. 3P of Prepress, Press, Postpress, etc., together with the fourth P of Data Processing data processing, became the new organization of CIP4, and the CIP4 organization basically provides specifications, and it is not a software or hardware producer itself, but CIP 4 Work order, changed to JDF document mode, the workpiece customer, name specifications, requirements and special requirements, precautions, even Lab color value concentration requirements and post-press processing parameters are also written, if the dot area ratio of each ink area is completed, It can be stored in the JDF (Job Definition Format) working document. The JDF document can be changed to the XML extensibility language. It can install more new work instructions and regulations than the PDF language used by CIP3, and the XML language can also be used. One of the languages used across multiple platforms.
First, the traditional ink preset method
Conventional ink presets are typically pre-adjusted by the operator of the press table based on experience. Before starting the machine, the approximate ink amount of each ink zone is estimated according to the distribution of the printing plate or the image of the proof, as a preset value of the ink amount, and further adjusted according to the specific change of the printed matter after the booting. Obviously, this kind of ink-discharging method is relatively rough, and the precision is greatly different due to different human operating experience and subjective knowledge. When the pre-discharge method is used from the start-up to the official printing, the paper consumption is large, and the adjustment time is cumbersome, and the work intensity of the machine operator is correspondingly increased.
Second, pre-inking technology based on CIP3/CIP4 standard
At present, CIP3 or CIP4, which is mentioned by most manufacturers, is the transmission of pre-discharge data and the maintenance of print quality stability. In terms of auxiliary ink discharge, the most important thing is to help the printing operator to save the inconsistency and waste of manual ink discharge. The required ink discharge data is directly obtained from the pre-press data file, and then transferred to the printing after a simple conversion. The ink control station of the machine makes the adjustment of the pre-discharge, because such an auxiliary ink-discharging method greatly saves time and thus improves the efficiency.
The pre-inking system of the offset press, in addition to the original integrated operating system, also has methods using other manufacturers' systems. The purpose is to be able to use the familiar visual operating system independently of the different printing press systems, so that not only can the pre-inking of the printing press be achieved, but also the printing machine can be connected to the printing machine for scanning guides and automatic feedback. Wait.
1. Pre-inking data generation
To pre-print the pre-discharge of the printing press, the most important thing is to transfer the pre-press large-format file to the corresponding conversion software and then to the printing machine operating system. However, the number of ink areas per color of the printing press is not the same for every device manufacturer. For Heidelberg's start-up, it is 32 ink zones each, and the width of each ink zone is 32.5mm, while Roland 700 is 34 ink zones, each of which has a width of 30 mm. Prior to the advent of CIP3, printer operators generally performed pre-inking operations based on the dot area ratio of each ink zone corresponding to each color plate. Press the button by hand to adjust the opening and closing degree of the ink key. Take the four-color printing machine with 32 ink keys as an example. Put four colors of ink at least once to move to 128 ink keys, and each ink key should be added again. The action of ink or ink reduction means that the printer operator must press the up and down keys to add or subtract ink.
In the era of hand-printing large version, the plate printed with the film was taken to the squeegee machine, and the dot area ratio of the entire layout was scanned according to the ink area of the printing machine to obtain the percentage of the dot area of each ink zone. The percentage of each ink zone is then passed to the press operating system, and the press can adjust how much ink each color and each color plate put. The plate scanner is a large scanner that measures the percentage of the plate's internet point in each ink zone.
Now that there is a large version of the file data, to get the dot area ratio of each ink zone, you only need to calculate the large version of the file. For the printing plate, the dots on the plate are not only different in size, but also each point is completely black, and it is also the smallest unit that accepts ink. These dots have a smaller size in the 1-bit Tiff file. The same point composition. As shown in Figure 1
In fact, the 1-bit Tiff file is to let the laser imagesetter or CTP platesetter know where to manage and where to do it. These points, regardless of their size, are black spots. After the information is transmitted to the plate, the main function is to accept the ink.
In summary, the percentage of ink dot points obtained from the squeegee machine or the percentage of ink dot dots calculated by the 1-bit Tiff file is based on the ratio of black (spot) and white (blank). The division, according to the size of the ink zone (inkzone) to calculate the amount of ink in each ink zone. Therefore, the pre-inking percentage can be calculated from the large version of the PDF file or from the 1-bit Tiff file generated by the RIP post-printing process. In order to achieve the purpose of data exchange, it must be written in a common format. The most common format is the PPF file format defined by CIP3, or the JDF file format of CIP4. Most of these standard formats can be obtained by RIP, and most of them can accept 1-bit Tiff or PDF large-format data files in terms of interface.
2. Transmission of pre-discharge data
With the pre-inking data, it is not possible to directly control the ink keys of the printing press. The dot area ratio of each ink zone is recorded in the PPF file, but the same effect can not be achieved by the printing presses of different manufacturers. The data on the PPF file obtained from the large version of the file is relatively fixed for the same type of printing machine. After the pre-discharge data is transmitted to the control machine of the printing press, it must be adjusted by the ink discharge curve of the printing machine operating system to ensure that the gap of the ink key pre-adjustment can get the effect we need.
At present, the software used to connect CIP3/4 PPF or JDF files to the press console at home and abroad is the InkZone series software developed by Digital Information Ltd. of Switzerland. The following uses InkZone software as an example to illustrate the transmission of pre-discharge data.
DI-Plot software is designed to increase the productivity of the printing industry. Its unique conversion and calculation tools can read 1-bit TIFF, 8 Bit TIFF, CIP3/4 format files, which can be converted to the required output formats such as CIP4/JDF, PDF, TIFF and more. Here, the DI-Plot reads the 1-bit Tiff file or the PPF file to obtain pre-drain data and stores it in .ink format. For example, after a print A has made a CTP version, an A0.ppf is generated, and the A0.ppf file is transferred to the DI-Plot software. The DI-Plot first converts A0.ppf into the InkZone internal file format A0. Ink, then converted to a machine-recognizable format by InkZone PERFECTOR software, InkZone PERFECTOR converts A0.ink to A0.hei if it is a Heidelberg press, and A0.man if it is a Manroland press, if it is Komori The machine is converted to A0.kom and the corresponding data is passed to the ink console of the press. If the data is adjusted by the operator during the printing process and the acceptable quality requirements are met, the set of adjusted ink control data (A1.hei or A1.man or A1.kom) will be stored back to InkZone PERFECTOR. In the hard disk, for future linearization.
However, due to the non-linear relationship between the ink volume of the ink fountain of the printing press and the nominal scale, the calculated ink data calculated by the layout information of the layout is linear data, and the machine is used because of the long service life and the equipment wear. The key is in a non-standard state, plus the influence of the printing material, ink, plate type, environment temperature and humidity, etc., it is very necessary to adjust and convert the pre-discharge data to make it The actual ink discharge data of the ink fountain tends to be consistent.
3. Method of stable ink control
Although there is a setting of the pre-inking curve, due to the influence of the structure of the ink path of the printing machine, the characteristics of the ink, the distribution of the layout and the speed of the printing machine, etc., just reaching the ideal concentration value cannot It is maintained until the end of printing. Therefore, various methods must be used to achieve stable and accurate ink control.
3.1 subjective visual method. This method is subjective to the human eye, but not necessarily fast. Because the human eye is the most sensitive but also the most fatigued, and to take care of the ink keys on the four color plates at the same time, with 32 ink keys per unit, there are 128 ink keys that need to be adjusted, although not every The ink keys need to be adjusted, but the workload is also quite large, and the judgment and experience of each printer captain are not the same, often resulting in quality instability.
3.2 instrument measurement method. This method is usually used by the printing operator to take the printed printed matter onto the sample stand, and use a densitometer or a spectrophotometer to scan each ink zone color block on the color guide to know which color plate and which ink key. Need to add and subtract ink, and then pass this information to the stepper motor on the ink button to adjust the amount of ink. There are also equipment manufacturers that have developed monitoring instruments that scan the color values of the entire print, rather than scanning a single color guide, such as Heidelberg's CPC system.
Third, summary
CIP3/4 ink preset technology is now more and more used in production, which can reduce the amount of paper and ink used, greatly reduce production costs and improve the competitiveness of enterprises. And the ink preset system using prepress documents is highly accurate. The improvement of precision means that the color effect of the sample can be achieved without multiple trial printing, which naturally reduces the paper and ink used in many trial printings. The main performances are as follows:
1 Shorten the start-up time and improve the efficiency of the press. An imported four-color printing machine can complete the single-sided four-color registration and color correction of the printing plate in 10 minutes, shortening the traditional upper version and color correction time, and adapting to the short-time living time requirement.
2 With the ink volume data optimization function, the accuracy of the ink amount preset and the accuracy of the ink amount control are improved. Since the introduction of the data process replaces the manual color correction link, it can ensure that the print and the print are consistent, and can be repeated repeatedly, and can meet the current high quality requirements of the customer.
3 reduce production costs. By reducing the number of trial prints and shortening the press preparation time, it means more time for normal production work. This reduces some of the fixed expenses that the company should pay, and greatly reduces production costs.
Therefore, the introduction of CIP3/4 technology has to be a major breakthrough in improving the quality of printed materials, reducing costs, increasing efficiency, expanding new markets, and improving the competitiveness of enterprises.