The word "photographic manuscript" is commonly used in the field of image production. Photographic manuscripts refer to opaque graphic documents with solid black blocks on a white, clean background. The resolution of the text draft output from the laser printer must be at least 600dpi before it can be used as a photographic original. Photographs copied or pictures output from the fax machine cannot be used as photographic originals because the density of these images is not large enough to make positive pictures.
The high-quality manuscript and the high-quality positive film produced from this manuscript determine the production quality of the pad, because if the manuscript is poor, there is no way to compensate when making the pad.
If possible, the size of the original is preferably twice the size of the printed product. Because if the size of the original is large, there are a lot of flaws that can be reduced when taking a reduced photograph, so that the resulting positive image is clear and the edge resolution is good.
Most manufacturers of printing plates have the ability to modify drafts or scan originals that do not meet photographic requirements through computer scanning, thereby making ideal photographic film.
Imaging system
There are many ways to make positive film, such as dry film production, direct film production, photo film production and laser output. If drawing software such as CorelDRAW, Adobe, Illustrator, and Freehand are used to create a 1: 1 manuscript, a laser printer or imagesetter can be used to output the film.
Dry film output system
The dry film output system uses thermal energy to copy the image on paper or film, the same principle as a fax machine imaging on fax paper. One drawback of the dry film output system is that the imaging paper cannot maintain opaque black, it will fade to brown, if only used once, then brown is not a problem, but if you want to save the paper for later use, you should use it instead Film, or save as an electronic file.
Direct output system
The direct film output system uses a computer to directly output photographic film without the need for photographic procedures. After the image is formed on the film, the carrier will take the film out of the phototypesetting device and put it into the automatic developing device. Because the film is never exposed to the air and is not contaminated by air dust, this film output system can ensure the cleanliness of the positive film. This film can be stored for a period of time without fading.
laser printer
Laser printers with a resolution of 600 dpi or higher can make photographic originals. The higher the resolution, the better the quality of the output film. Coated paper works best. Inkjet printers are not suitable for outputting photographic manuscripts because the density of the output manuscripts is insufficient.
There are many kinds of special papers or transparent materials suitable for output from laser printers on the market, and the images output by these special papers have good quality, high density and good covering ability. It is best not to use a transparent acetate film for laser printing output, because the output image density is not enough, the image coverage is not good, you can also stack the same output acetate film with two claws to increase the image density.
Laser-printed documents are not as good as photographic manuscripts from imagesetters, especially for printing fine lines or small-size images. Usually the density of the image is not enough and the hiding is not good. In order to make up for this defect, the manufacturer has specially developed and produced a post-treatment spray and coating material. After the laser printer outputs the photo manuscript, the spray can be sprayed on the image surface, which helps to improve the hiding power of the image.
Plate-making camera
Photographic manuscripts are used in plate-making photography. Place the manuscripts in the copy frame and perform photosensitive photography according to the required magnification. According to the type of film, make a positive or negative film. The photosensitive film after development is automatically developed or put into the development tray for development. The film may be contaminated by the surrounding environment during the development process, but this method is still adopted by most people. One of its advantages is that it does not require all manuscripts to be produced by a computer.
Producer
Some printing factories cannot produce photographic film by themselves, and need to go to the outside production company or graphic production room to make the film. Generally, the production of original manuscripts is priced by the hour, while the yangyang photo film is priced by area.
Film positioning
Regardless of the method used to make the positive film, the positioning of the film is very important. In pad printing, the direction of the emulsion side of the film should be ensured, so that the emulsion side and the pad are in close contact during exposure and printing.
Because different printing processes have different film orientations, people often confuse film orientation. The film orientation diagram describes how the image should be oriented during exposure exposure.
The orientation diagram of the film is usually based on "emulsion facing down", which means that when we look at the film, the above is the image we need to print, and the emulsion should be on the back of the film.
When printing a positive image on a special paper with a laser printer, the printed image should be reversed, because when the image of the printed paper is brought face down into contact with the pad, the toner will directly contact the surface of the plate.
When using a dry film imaging system, the image is integrated with the film, rather than attached to the surface, so there is no problem with the orientation of the film. This imaging method sometimes causes the phenomenon of "halo" of the image, and the edge definition is not good, especially when printing small-sized symbols or fine lines. This problem is very prominent.
Be sure to keep the non-graphic parts of the film as clean as possible, especially when printing plastic plates. Before printing, be sure to remove all stains, ink stains, residual emulsion, etc., especially pay attention to the image area to be imprinted by the pad.
Image distortion
The printing head will produce some deformation when printing on the surface of the printing material, but sometimes it needs some deformation of the original, such as printing on the combined triangular surface, printing on the convex surface or printing on the edge, all need some deformation of the original .
There are some tips on manuscript distortion, which can help the printer decide how to do the distortion and where to do it to save time.
1. Make some small grids on the pad. The size of the small grid depends on the size of the printed image. A square with a side length of 5 mm is usually used. Use different types and shapes of printing heads to print multiple times, from which you will find the printing pads with the smallest deformation, then use this as a reference standard to perform the necessary deformation on the original, one small square at a time as the deformation unit . When experimenting with each type of pad, make sure to record what type of pad, where to print, how much compression, etc. The steps to make a deformed manuscript using a small grid method are as follows:
· Print small grid;
· Measure the size of each small square deformation on the printed object;
· Make a deformed grid pattern in the computer by using the change value of the measured small squares;
Use the grid of the variable table to make a deformed image for printing;
· Print on the object with an image deformed original.
2. Use the "reverse printing" method to print individual letters. Circle the letters to be printed and print the printing head at high speed so that it can completely cover the printing area. Apply the ink gently to the raised letters, and then press the pad on the ink-coated letters to take up the ink and finally print it on white paper. Such a deformed letter is printed on the paper, and the letter is input into the computer by a scanner, and a deformed original is released by the computer. The specific steps are as follows:
· Lightly spray the letters with a small amount of ink or other transferable paint;
· Use the printing head to bring up the ink on the letters;
The letter pattern on the printing head is printed on the paper, and the printed deformed pattern is input into the computer with a scanner, and an image deformed manuscript is created on the computer for printing the printing plate. Use raised images to print raised letters.
Original image size
During exposure exposure, the original is rotated on the steel plate (plastic plate), and its size should not exceed the area of ​​the steel plate (plastic plate) or the maximum area printed by the printing machine. In the open printing system, the length and width of the original image should be controlled within 80% of the maximum length and width of the machine. If this value is exceeded, it will cause uneven ink coating, or the image is too close to the steel plate (plastic plate) ) Edge, causing the pad to carry a lot of ink that should not be brought up. In a closed printing system, the image size should not exceed 90% of the diameter of the ink tank.
When placing originals, also consider the working direction of the machine's ink sheet. If there are straight lines in the original, when rotating the original, these straight lines should be perpendicular to the working direction of the inking plate, or have a small angle to the vertical direction. It is necessary to match the eroded image in the pad with the working method of the ink-coated plate.
The best way is to check the positioning of the original image twice before printing the printing plate. Place the laser prints or manuscripts together on the table to form an observation whole, according to the length direction of the ink coating plate (align the center axis of each pad in the multi-color printing machine), check whether all the images Straight line.
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