The most popular stereo printing technology reprod

2022-08-09
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Stereo printing process: reproduce three-dimensional color (middle)

2 Plate making and printing process

due to the delicate pixels of stereo images and the amplification of cylindrical grating, the number of plate making lines must be more than 120 lines/cm. Stereoscopic printing is different from ordinary color printing at the same angle, and the blue and black versions should adopt the same eye angle. In addition, stereo printing with different grid spacing should have different line combination angles of yellow, magenta, cyan and black plates to avoid interference fringes. The commonly used adding angle of printing manufacturers is:

0.6 grid spacing/cm, 100 lines/cm color separation, then the adding angle is y81, M36, C66, K66

0.44 grid pitch/cm, 58 lines/cm color separation, then the angle is Y50, M20, C65, K65

0.31 grid pitch/cm, 81 lines/cm color separation, then the angle is y66, M22, C51, K51

since the stereoscopic manuscript is composed of closely arranged pixels, and the cylindrical mirror plate is also compounded after plate making and printing, when selecting the line angle, in addition to considering the moire formed between plates, attention should also be paid to the normal protection of the hydraulic universal testing machine for each screen angle. The following problems should be paid attention to: timely clearing the moire formed by other parts such as concrete samples and iron filings, pixel lines and cylindrical mirror plate lines. For example, 0 degree should not be selected for stereo printing, because the horizontal line is the most obvious, and 0 degree is orthogonal to the pixel line and cylindrical mirror line, which interferes with the clarity and depth of the image. In stereoscopic printing, the green and black plates have the same angle, which is determined by its own characteristics. Because the stereoscopic printing products are mostly compounded with plastic plates, and most of the column mirror plates have a certain gray level, and the stereoscopic printing uses a very fine 300 line screen, which only needs to be exposed to 85% or 90% when printing, otherwise it is easy to paste the plate when printing, so it is necessary to increase the color amount of the dark tone area to achieve the effect of 9 ~ 9.5%. Therefore, the field density of color ink in stereo printing is higher than that in plane four-color printing. Generally:

offset lithography: y:1 ~ 1.1, m:1.4 ~ 1.5, c:1.5 ~ 1.6

stereo printing: y:1.33 ~ 1.35, m:1.31 ~ 1.33, c:2

if the three-color printing ink is close to neutral gray after overprinting, in order to reduce the error caused by the fourth overprint, there is no need to print the black version again. You can take the same angle between the black version and the green version for flexibility. In small format continuous exposure, the temperature of the exposure light source will cause the negative film to shrink, resulting in the change of the grid distance between the front and back frames, which will affect the accuracy of printing orientation. Therefore, it is best to connect the color separations into a whole negative for printing. When copying a positive image, it is necessary to close a line sheet with the same width as the grid distance between the negative film and the photosensitive film. The PS version with good hierarchical expressiveness should be used for the sun printing plate. The printing method selected for stereoscopic printing should ensure that the stereoscopic sense will not be lost due to printing, and the requirements of good overprint accuracy and large amount of printing are suitable. Lithographic offset printing: plate making, printing overprint accuracy, printing resistance are relatively good, prints have a good three-dimensional sense, plate making is stable, and can be mass produced. Photogravure: the accuracy of plate making and printing overprint is not very good, the printing resistance is good, the three-dimensional effect of printing is good, but the multi-color printing effect is not good. Collotype: the plate making and modulation are unstable, the printing resistance is low, the printing accuracy of the printed matter is good, and the three-dimensional sense is good, but it is not suitable for mass production. The quality of stereoscopic printing has a significant impact on the intuitive effect of stereoscopic pictures. Due to the focusing and blocking effect of the grating, it is required that the line is clear and the overprint is accurate, the overprint error is not allowed to exceed 0.02mm, and the printing ink is required to be bright and clean without fading. The high-precision four-color printing machine is used for printing. The gauge lines must meet strictly, and the workshop must have constant temperature and humidity conditions. Compared with the above conditions, offset plate making method is usually used for stereoscopic photos. The three-dimensional image negatives taken are separated by electronic color separation or direct photographic process

3. Stereoscopic printing materials and technology

(1. The cooperation with parts manufacturers and automobile OEMs is getting closer and closer) paper. The printing paper shall be compact, bright and clean, flat and have small flexibility; Coated paper or cardboard is usually used. (2) Grating material. There are mainly hard plastic three-dimensional grating and soft plastic three-dimensional grating. Hard plastic three-dimensional grating sheet is made of polystyrene material through injection molding to form concave convex column mirror grating sheet. Polystyrene is colorless and transparent, with a refractive index of 1.59 ~ 1.6, and has no ductility and flammability. Because of such a high refractive index, it has good luster. The chemical properties of polystyrene are resistant to some mineral oils, organic acids, alkalis, salts, lower alcohols and their aqueous solutions. In some cases, the corrosion degree of polystyrene by chemical reagents can be reduced by annealing, stress relief and other measures. Soft plastic three-dimensional grating sheet is made of PVC sheet base and pressed into soft plastic three-dimensional grating sheet by metal grating roller or grating plate. Mr. Wang Ming is a deputy general manager and senior engineer grating sheet. Polyvinyl chloride (PVC) is a polymer compound formed by polymerization of chlorinated alkene, which is difficult to burn. PVC can be made into colorless, transparent and glossy films, and can produce films with various softness according to the content of plasticizer. This material has high fastness after pulse heat sealing, high-frequency heat sealing and bonding. PVC has good chemical resistance, but poor thermal stability and light resistance

(2) ink. At present, some ink manufacturers can provide inks and additives suitable for stereo printing, and some manufacturers have developed new ink production lines. However, it should be noted that stereo printing ink is not foaming ink. In fact, any visible degree of foaming will affect the clarity and three-dimensional effect. The curing temperature of three-dimensional printing ink is within the curing range of standard plastic ink (149 ~ 171 ℃), but it must be increased to the curing temperature suitable for ultra thick ink layer. If the ink layer is completely cured, 3D ink will have the same elasticity as standard plastic ink. Although three-dimensional printing ink is not common, this ink is very different from the thick plastic ink layer commonly used by people in 2015. If the operation is correct, the three-dimensional printing image will have distinct fine layers and clear edges. The printing edge will bulge vertically from the fabric surface, and the ink wall is very smooth. Although this kind of ink is very thick and the template is very thick, 3D printing can still print exciting fine levels and printed matter

(3) adhesive. The function of the adhesive is to make the printed matter and the grating stick together firmly, and to protect the ink layer from discoloration at high temperature

(4) problems needing attention in stereo printing

photography adopts single lens machine or multi lens machine, which requires the camera to have high accuracy and avoid errors caused by vibration. And accurately adjust the focal length, angle and grating data moving distance; Improve the accuracy of color separation, hanging and copying in plate making. 300 line points are required to be solid, and the scenery image maintains rich levels; Chromatic printing must be carried out as planned to avoid paper stretching and causing inaccurate chromatic printing; The grating spacing and angle have high accuracy, and the compound molding requires accurate positioning. Hard plastic and soft plastic have better transparency

(to be continued)

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