Analysis of Common Problems in Output Film

Due to factors such as compatibility or compatibility between software and software, the output film cannot achieve the expected effect, which may cause human and material resources in the production process. The waste.

The correct output of four-color film film is crucial, and its quality is related to the final effect of the print. The trend in today's printing industry is that it is not enough for a good designer to engage in creation and design, but also to have a series of knowledge about output in order to avoid problems in the production process due to the operation of the producer or the exporter. Mistakes cause a waste of human and material resources. This phenomenon is common in production practice. We often encounter such problems in practical work. Some advertisements that are in urgent need of seeing large samples cannot be produced at the output center, or the films that come out do not meet the requirements, resulting in a series of links Discontinue production, causing irreparable damage to customers and printing plants. Therefore, starting from the actual production, I summed up some of the problems that often arise in the output process and solutions.

One. Types of photosetters

Phototypesetters mainly include winch type and drum type, and the winch type photosetter has relatively low accuracy. The drum phototypesetter is divided into two types: inner drum type and outer drum type. The outer drum type is faster but the precision is slightly lower. The inner drum type has high precision but slower speed. The experimentally measured high-definition inner cylinder drum phototypesetter output 4 films whose repositioning accuracy can reach ± ​​5μm.

Two ways to improve the output efficiency of the photosetter

(1) Sometimes changing the direction of the phototype page can greatly increase the imaging speed. For example, a page such as stationery, with the long edge in the axial direction during exposure imaging, saves both exposure time and material.

(2) First image the successful job, temporarily remove the problematic job, and finally deal with the problematic job.

Three. Note that the imagesetter should pay attention to the output film

Laser photo-discharge output film is an important part of the prepress output process. To output high-quality platemaking negatives, in addition to setting the output parameters correctly, it is also necessary to take corresponding technical measures according to the characteristics of the photocopies. Therefore, it is necessary to understand and understand the technical requirements of the photolithographic films.

According to the different characteristics of the light source of the imagesetter, the laser photo-taking film is generally divided into two types, namely HN and red laser LD. The direction of the film surface is divided into inward or outward, and an imagesetter can only use the inner or outer roll. One of the films. The film used in the conventional phototypesetting machine has two types of axis, the small axis is 2.0 inches (51mm) long and the large axis is 2.8 inches (71.9mm) long. Soft and hard flange refers to whether there are black hard plastic plugs at both ends of the film. Generally on the same photosetter, the hard and soft flanged films can be used interchangeably.

Each imagesetter can only use film whose width is smaller than its maximum size. The length of the film that the imagesetter can install is determined by the size of its cassette.

When outputting the film, make sure that the laser imagesetter is in an absolutely normal and good working condition, and perform periodic calibration of the laser imagesetter. From the perspective of optimizing the operations of the imagesetter, periodic calibration of the equipment ensures that the equipment produces the correct film density. A small problem with the imagesetter can cause film waste and drop efficiency. It can also result in excessively large film bottom ash, insufficient density, uneven layout, inaccuracies in the field, missing layers, missing meshes, stencils, etc. .

Photographic film in use should pay attention to the following questions:

1. Although the ordinary photocopying film is a bright room film, the loading process can be completed under the indoor light source, but in the actual production should still strictly abide by the operating procedures, according to the requirements of the film loaded in the loading box, the stage cover , Tighten the screws on both sides of the box (pay attention to balance force on both sides to maintain balance) and then tear the film lead so that the exposed film on both sides of the film is parallel, the width of 1.5 ~ 2cm, in the process of handling to support The bottom of the box prevents the film from dislocating.
2. Before each batch of laser illuminating film is put into use, basic density testing and linearization of the dots should be carried out. Then, corresponding technological measures are taken according to the test results, such as adjusting the laser focal length, exposure amount, development fixing temperature and time. In order to achieve standardized and scientific production, prevent the formation of non-lattice products.

(1) The film density is divided into high density and low density. Low density refers to the density at which the film is completely unexposed after rinsing, typically around 0.05. The lower the low density, the more transparent the film is and the better the quality of the printing screen. High density refers to the density of the film after it has been washed at 100% exposure. The printing film used in traditional coated paper requires a high density value of not less than 3.5, usually 3.5 to 4.5. This ensures that the image information on the film is well transferred to the printing plate during printing. When printing on newsprint and offset paper (including map paper), the high density of the paper may be appropriately reduced due to the strong ink absorption and high printing speed.

(2) Linearization refers to the process of color separation. It is required to ensure that the dot values ​​set in the computer can be truly reflected on the printed film. Take 50% neutral ash as an example, where 50% of screen points are required on the computer, the output must be 50% on the printed film, and the dot error should not exceed 1% of the soil. Otherwise, the distortion of the printed image will be caused. This is especially evident in color four-color printing. However, it is difficult to ensure the stability of the film development and fixing conditions. Therefore, it is more stringent to test the linearization every day.

3. Adjust the concentration and temperature of the fixing solution and the fixing time.

(1) Other conditions remain the same. The higher the developer concentration, the higher the temperature, the higher the density of the film. If you use a domestic developer (for example: Aibixi SH-1000) to wash the film, the liquid is generally diluted 1:4 to 1:3. It should be noted that if the developing temperature is set too high, the developer will evaporate and oxidize. The speed is too fast and fails, resulting in excessive film fog, while the high density is not up to the requirements. The recommended temperature is 34-36°C, and the density and linearity are measured again when the development temperature is stable and the set temperature is reached.

(2) Other conditions remain the same, the higher the fixing solution concentration, the higher the temperature, the lower the film base fog (low density), the dilution ratio of the domestically produced fixing solution is 1:4, too high fixing temperature setting (or excessively high temperatures in summer) can cause the fixing fluid to fail due to evaporation or oxidation too quickly, resulting in excessively high film haze. At the same time, the high density may not meet the requirements, and liquid crystals of the liquid may adhere to the fixing roller. The film is scratched. Therefore, the fixing temperature is 28 to 32°C, and the fixing time is 30 to 35 seconds.

4. The laser radiography film contains an anti-halation layer, some of which will fall off in the process of fixing and washing, forming a light blue water spot on the film base, which can be eliminated by adding an appropriate amount of hardener in the fixing solution. The washing tank must be kept clean. After the work is completed, the water in the sink should be drained and wiped with a clean gauze. Before each water addition, remove some water to remove rust, and at least stick to the water roller once a week.

In short, in the process of using laser to illuminate film, only by mastering its characteristics and properly outputting the output technology and operating technology can effectively guarantee the quality of the laser illumination and output efficiency.

Source: China Packaging Magazine Institute of Printing and Packaging Engineering, Beijing Institute of Graphic Arts