The use of lasers as a high-performance means for plate production is the goal of long-term unremitting efforts in the prepress processing and platemaking fields. As a high-energy, high-performance recording tool, Laser Engraver has been playing an increasingly important role in the fields of offset printing and gravure printing since the 1970s. On the basis of computer graphics and text information processing, the use of lasers to output the graphics and text records of films and offset printing plates is the most common and most promising method of offset platemaking. The so-called "CTFilm" and "CTPlate" naturally include laser plate records.
As we all know, the mechanical electromagnetic gravure electronic engraving machine was invented in 1962 by the German company Hell GmbH. This is very close to the invention of the laser. In fact, the company's technicians tried to engraving copper-plated drums with lasers at that time, but failed due to the high reflectivity of copper to light. They turned to high-energy electron beam engraving research and achieved success.
Laser recording of gravure printing plates began in 1977. At that time, the British company Crosfield Electronics had used Laser Engraver to sculpt holes on a gravure cylinder with a polymer resin layer to make a gravure cylinder. Although the system has not been put into practical use in large quantities due to quality stability and other reasons, as a beneficial technical research and exploration, it has pointed out ways for the continued development of laser gravure plates.
At the printing event Drupa2000 held in Düsseldorf, Germany in May 2000, people saw that the laser plate recording technology has fully entered the practical stage. In addition to the technology used for lithographic Laser Engraver becoming a hot spot, many manufacturers have Launched laser plate-making equipment for gravure printing plates and flexographic plates, which became a highlight of CTC (Computer To Cylinder).
As far as the types of gravure mesh cavities are concerned, there are usually four types, namely: variable mesh cavities, variable depth cavities, variable mesh cavities with both area and recessed depth, and frequency modulated cells. At the current level of technological development, laser engraving of these four types of cells has been achieved.
1. Variable area mesh
As the name implies, this type of network cavity reproduces the gradation of the image only by changing its opening area. The area of the mesh in the deep color is larger, while the area of the mesh in the light color is smaller, and the recessed depth of the mesh is unchanged. In terms of this feature, it is similar to the principle of image reproduction of offset screen dots. Therefore, this type of intaglio is also called "dot intaglio".