Letterpress, lithographic (offset) is the use of dot area size to express the level of print, but the gravure is to use the recess to express the level. The shape of this recess has the following differences: "the surface area of ​​the recess is the same and its depth is different", "the depth is constant and the surface area is different", and "the depth and the surface area are all different". The production method of the printing plate (called gravure printing plate in the gravure printing) is very complicated compared with other printing methods (Fig. 1). Therefore, the manufacturing method of the gravure printing film base plate is also complicated and difficult.

Now, the shapes of the ink fountains listed above can be made. The history of gravure printing technology should be the history of the development of diverse bottom plates and plates.

On the other hand, in the 1960s, a monochromatic image of a film master (photosensitive film) was read as a reflection density, and this density signal was changed to the strength of an electric signal, and a copper pin on the surface of a roller was carved with a jewel needle and developed. Electronic engraving technology. In the basic technology of the recent CTP, the gravure printing method is quite advanced. The technicians in the gravure field are not surprised at the CTPization. From the background of the development of intaglio printing technology, the solution of ink groove formation instability and ring printing (wood grain, printed fabrics, wallpaper, packaging and printing, etc.) with gravure printing features is expected to be realized practically due to the ingenious market and technology. Combine.

Now, the technological environment surrounding gravure printing has rapidly progressed with the pre-press electronicization and filmlessness. The CTP process of cylinder production is not only an engraving method, but the development of the laser method has also promoted the drum processing technology into a more diversified era.

Gravure plate making

In the gravure platemaking method, the traditional plate-making method has the same ink groove area, and uses ink tank depth to express the printing level. The basic version of this method is not a dot, but it is continuous and shaded. The image of the base plate with shades was copied with ultraviolet rays on a resist film (carbon paper) used to corrode the copper plated layer of the platen. The resist film was wrapped on a roller, developed with hot water, and chemically etched with a ferric chloride solution to form ink tanks with different depths.

However, there has been almost no use of continuous-tone masters. Carbon paper has rarely been used except for use in the production of rollers for publication.

The current method can be roughly divided into two types: one is the use of a film master in the process of making a plate, and the same method of making halftone masters as the offset master; the other is to digitally process the image and then perform a filmless drum production method.

The tendency toward filmlessness has rapidly developed in the fields of packaging, printing, and special printing. The reason for this is the recent increase in computer functions, miniaturization, and low price, and it has indeed promoted filmlessness in the field of gravure printing.

The status of publishing gravure plates

The history of publishing gravure platemaking technology was dominated by the use of carbon paper by the mid-1970s, so film bottom plate images were continuous. During this period, an electronic engraving device was developed, starting with the electronic engraving method using continuous film (actually a photographic film in contact with the copy), and it was also possible to use offset halftone printing in the early 1980s. Now, the gravure printing publication in Europe and America can be said to be 100% electronic engraving.

Japan's domestic platemaking methods include: (1) etching methods using offset printing plates; (2) electronic engraving methods using offset printing plates; (3) non-film electronic engraving methods (gravure CTP) using digital data. According to the actual situation can be flexibly selected. Among them, the filmless electronic engraving method developed rapidly, accounting for about 50% of the total.

In the field of gravure printing, there is almost no need to use the laser method (corrosion method) in the packaging field. The reasons are (1) the laser method is relatively new; (2) the roller is large and the handling is difficult; (3) the minimum is on a roller. The 32-page (L-shaped) size requires high-performance image processing technology to create a 76-page ink tank on a large roller. (4) Large equipment investment is a problem unique to publishing and printing.

Now, as a manufacturer of electronic engraving machine systems, there are Ohio Electronic Inglebaz of the United States and Haier Gravure Systems of Heidelberg of Germany.

The status of package gravure platemaking

In addition to printing in gravure printing, there are package printing and special printing. Packaging of all paper containers such as printing of plastic films represented by fruit bags and instant noodle bags, cartons of fruit, cartons of thin paper, and the like are packaged. In this area, many printing companies use platemaking machines. It also includes special printing (labels, forms, securities, decorative materials, wallpaper, printed fabrics, etc.). Since there are various requirements for printed products, more drums are produced in this area than the printed ones. the way. Including (1) dot gravure printing method (using gravure printing screen); (2) using offset master and electronic engraving using digital data; (3) laser plate making using photosensitizer (digital data); (4) use Black-painted laser plate making method (digital data); (5) Laser plate making method (digital data) using plated alloy.

The manufacturing unit of the device is also the same as the electronic engraving method. In addition to the aforementioned two companies, there are screen manufacturing companies in Japan. The sensitizer laser method is the Japan New Valley Research Institute, and the black lacquer method is the German Sheppard Ohio Company. , electroplating method is Switzerland's MDC Maxette Uyala company.

The plate-making software related to packaging has the same pattern of multiple imposition (even drying) and patternless jointless belts (pattern without breaks), but these softwares are not developed by the manufacturer of the device. And in the printing, its characteristic is multi-purpose, used for 6 color, 7 color print occasions. At this point, it is very different from publishing gravure.