Analysis of common problems in film output
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Pre-press graphics processing commonly used hardware and software due to compatibility or software compatibility, text encoding compatibility and other factors will cause the output film to achieve the expected effect, resulting in manpower, material resources, etc. in the production process Waste of resources.
The correct output of four-color film film is very important, and its quality is related to the final effect of printed matter. So the trend in the printing industry today is: a good design and production staff will only be creative and design is not enough, but also have output. A series of knowledge to avoid the waste of manpower and material resources in the production process due to the operation problems of the producers or the mistakes of the exporters. This kind of phenomenon is not uncommon in production practice. We often encounter such problems in actual work. We urgently need to see large-scale advertisements, but we can’t send them out at the output center, or the films that come out do not meet the requirements, causing the subsequent series to stop production. , bringing irreparable damage to customers and printing plants. Therefore, from the actual production, I have summarized some of the problems and solutions that often occur in the film output process.
1. Regular calibration with the machine
When outputting film, first ensure that the laser imagesetter is in an absolutely normal and good working condition, and the laser imagesetter is regularly calibrated. This is the basic premise of all work. From the perspective of optimizing the imagesetter operation, periodic calibration of the equipment ensures that the equipment produces the correct film density. The small problem of the photo-distribution machine may cause waste of film and decrease of filming efficiency, and may also lead to excessive film bottom ash, insufficient density, uneven layout, unrealized ground, layer loss, net, paste, etc. phenomenon.
2. Method for improving the output efficiency of the imagesetter
2.1 Sometimes changing the orientation of the photo page can greatly increase the imaging speed. For example, a page such as letter paper, which has a long side along the axial direction during exposure imaging, saves both exposure time and material.
2.2 Firstly image the smooth progress of the job, temporarily remove the problematic work, and finally deal with the problematic work.
3. Problems that should be paid attention to when outputting the film according to the arrangement machine
In order to output high-quality plate-making negative film, in addition to correctly setting the output parameters, it is necessary to take corresponding technical measures according to the characteristics of the photo film, so it is necessary to know and understand the technical requirements of the film.
According to the characteristics of the light source of the imagesetter, the laser phototype film is generally divided into two types: HN and red laser LD. The winding direction of the film surface is divided into inward or outward direction, and one phototype machine can only use inner or outer volume. One of the films. The film used in the common imagesetter has two axes, 2.0 inches (5lmm) for the small axis and 2.8 inches (71.9mm) for the large axis.
Only each film with a width specification smaller than its maximum size can be used for each imagesetter. The length of the film that can be installed in the imagesetter is determined by the size of the cassette.
3.1 Although the general photo film is a bright room film, the film loading process can be completed under the indoor light source. However, in actual production, the operating procedures should be strictly observed, and the film should be loaded into the loading box and the cover closed. Tighten the screws on both sides of the top of the box (note that the sides are evenly balanced), then tear off the film leader so that the film exposed on the film opening is parallel on both sides, and the width is about 1.5~2cm. Hold the bottom of the box during handling to prevent the film from being exposed due to falling off.
3.2 Each batch of laser photo film should be subjected to basic density test and dot linearization before being put into use, and then take corresponding technical measures according to the test results, such as adjusting the laser focal length, exposure amount, developing fixing temperature and time. Standardize and scientifically produce products to prevent the production of substandard products.
(1) Film density is divided into high density and low density. Low density refers to the density of the film that is completely unexposed after rinsing, generally around 0.05. The lower the low density value, the clearer the film is, and the quality of the printing plate is good. High density refers to the density of the film after it has been washed at 100% exposure. Generally, the printing film used for the printing of coated paper requires a high density value of not less than 3.5, usually 3.5 to 4.5, so that the image information on the film can be well transferred to the printing plate during printing. When printing newsprint and offset paper (including map paper), the high density of paper can be appropriately reduced due to the strong ink absorption and high printing speed.
(2) Linearization means that the color separation plate is required to ensure that the dot values set in the computer can be truly reflected on the printed film. Taking 50% neutral ash as an example, where 50% of the dots on the computer are required, the output to the printed film must also be 50%, and the dot error should not exceed ±1%. Otherwise, the distortion of the printed image will be caused. This is especially true in color four-color printing. However, the stability of film development and fixing conditions is difficult to guarantee, so it is more rigorous to measure the linearization every day.
3.3 Adjust the concentration, temperature and fixing time of the fixing solution.
(1) Other conditions are constant, the higher the concentration of the developer, the higher the temperature, the higher the density of the film. If the film is washed with a domestic developer (for example, Abbie SH-1000), the solution should be diluted 1:4 to 1:3. It should be noted that setting the developer temperature too high will cause the developer to evaporate and oxidize. The speed is too fast and fails, causing the film fog to be too high, and the high density is not up to the requirement. The recommended temperature is 34 to 36 ° C, and the density and linearization are measured when the development temperature is stable and the set temperature is reached.
(2) Other conditions are unchanged, the higher the concentration of the fixing solution is, the higher the temperature is, the lower the fog density (low density) of the film base is. The dilution ratio of the domestic fixing solution is 1:4, and the fixing temperature setting is too high. (or too high temperatures in summer) will cause the fixing solution to fail due to evaporation or oxidation too fast, resulting in high fog fogging, and will also make the high density less than required, and will form a liquid crystal attached to the fixing roller. The film is scratched, so the recommended fixing temperature is 28 to 32 ° C and the fixing time is 30 to 35 seconds.
4The laser photo film contains an antihalation layer. Some of it will fall off during the process of fixing and washing, and a light blue water spot will be formed on the substrate. It can be removed by adding an appropriate amount of hardener to the fixing solution. The washing tank should be kept clean at all times. After the work is finished, drain the water from the sink and dry it with a clean gauze. Before each water is added, the water should be drained to remove the rust. At least once a week, the water roller should be cleaned.
In short, only by correctly mastering the characteristics of laser phototype film, and correctly controlling the output process and operation technology, can effectively ensure the quality of laser phototypesetting and improve output efficiency.