People can observe at the same distance from the printed matter without distortion, and can reproduce it accurately. The hue and saturation are in the normal range, so the relationship between the screen and the observation distance should be fully considered.
2. Selection of screening angle:
Choosing a good screening angle is an important link to reduce turtle grain phenomenon. In color reproduction, different screening angles must be used for color separation of different colors, and moire fringes should be suppressed as much as possible. Therefore, for eye-catching color (cyan, magenta, black) version, the screening angle is 30. The yellow version is an inconspicuous color. You can write 15 the difference of other colors, such as the specific screening angle of four-tone screening.
3. The application of color inkjet printing technology in the production of outdoor advertising light boxes;
Inkjet printing is a pressureless printing method, which uses computer to control the tiny ink flow from nozzle to substrate to obtain characters and images. It integrates electronics, machinery, fluid, ultrasound, microcomputer and other disciplines, and has become one of the high-tech in the field of color printing. In recent years, large-scale outdoor advertisements have adopted inkjet printing technology, which makes the tone level, clarity and color saturation of outdoor advertising light box patterns almost perfect.
(1) typesetting system for inkjet printing;
The inkjet printing system consists of system controller, inkjet controller, nozzle, substrate driving mechanism, substrate and so on.
The output dot of inkjet printing system is the key factor to determine the printing quality. The size of ink dots is expressed in dots per inch. Color map printing generally includes 300dpi, 600dpi, 720dpi, 1024dpi, etc. Some large-format advertising posters can be printed with 9 ~ 72 dpi.
(2) Type of inkjet printer:
Inkjet printers can be divided into two categories: continuous inkjet printers and intermittent inkjet printers.
(3) color inkjet printing:
The host computer of color inkjet printing system receives color information through various information sources, such as color graphic terminal, color scanner, digital camera, color word processor and other analog or digital manuscript collection systems. The information source sends the information of the three primary colors of spring, namely red, green and blue, to the printer interface, and stores the information to be copied in the main memory. Then, the color converter converts the information of red, green and blue into color separation and screening signals of cyan, magenta, yellow and black ink, and then the gray controller controls neutral gray, and sends the ink signals of the above four colors to the electrodes of the corresponding color nozzles to control the nozzles to eject ink.
(4) Inkjet printing materials:
A. coloring materials:
Advanced special inks of yellow (Y), magenta (M), cyan (C) and black (K) suitable for color inkjet must have stable printing performance, non-toxicity, non-clogging nozzle and good ejection performance, such as the performance index of a liquid ink.
At present, a wax-based solid ink is widely used, and its pigment is pigment, which has excellent light resistance and is not easy to fade. The printing process is fixed on the surface of the substrate and will not penetrate into it, so the imprint has good clarity.
B. printed materials:
The types of printing materials that can be used are mostly special paper, spray-painted film and outdoor advertising lamp box cloth. As far as paper is concerned, in order to prevent the spread of ink spots on the paper, the paper surface is required to be smooth, and high-gloss photographic paper is generally used, and its surface is coated with an extremely thin transparent coating.
4. The application of color screen printing technology in the production of outdoor advertising light boxes;
Screen printing is an ancient and unique printing technology with advantages that other printing methods do not have. It occupies a considerable proportion in all kinds of outdoor advertisements and has the advantages of batch reproduction and low cost.
(1) The key of color screen printing lies in the plate-making of color continuous tone images, and the following issues need to be considered in the plate-making process:
A. the scale of the screen must be considered when enlarging the image.
B. Under normal circumstances, the manuscript is positive, but if printed on transparent materials, the manuscript should be positive.
C. The screen angles of yellow, magenta, cyan and black films should not only avoid mutual interference and moire, but also consider the influence of the square doors of the screen on color reproduction.
(2) Matters needing attention in material selection and process:
A. All four mesh frames should be metal frames with the same specifications.
B. Screen printing should have high dyeing accuracy and prevent halo, and its mesh number should be determined according to the magnification of printed patterns.
C. When pulling the net, the four boards shall be carried out in the same equipment or under the same conditions. It is appropriate to adopt the method of "one net stretching four" to ensure the tension and accuracy of the four grids are consistent. The stretched net should be placed for 1 ~ 2 days before use to ensure full "relaxation".
D the template is made by direct method, and the coating thickness of photosensitive adhesive should be uniform. When printing, keep pumping, light source, exposure time and development in the same step (with the plate ladder). Templates should be stored and used under specified conditions.
E. large or precision screen printing machine is used for printing, and the temperature in the operation room is controlled at 18℃ ~ 25℃, and the humidity is controlled at 50% ~ 70%.
F the screen spacing of printing should be as small as possible to improve the overprinter accuracy and reduce moire phenomenon.
G. the scraper length should be consistent and the pressure should be small. The angle of the scraping blade is about 75 ~ 80, and the hardness is slightly higher, that is, the Shore hardness is about 70, and the blade should be sharp.
H uniform ink should be thin (about 20μm) and uniform to prevent ink from filling the grid.
First, the choice of ink must be matched with the materials. The spectral characteristics of tricolor ink are better, the transparency is higher, and the viscosity can be slightly higher, so that the dot can stand up and avoid expansion. It is recommended to use ink that dries slowly and prints quickly on the printing plate.
J. Before printing, all kinds of printing materials must be treated with material adaptability.
K. Generally, the printing color sequence is to print the dark non-main color first, and then the main color, which is convenient for overprinting. If the color sequence is printed on transparent plastic materials, it should be overused, and the background color should be printed first, and then overprinted according to the color sequence.
The design of outdoor advertising light box seems simple, but in fact it is very particular. Good design style and pattern configuration can determine the quality of outdoor advertising light boxes.