With the continuous introduction of direct imaging (DI) presses, the industry's definition of "digital printing" has become increasingly vague. Up to now, 10 manufacturers have been able to produce DI printers, and the models are also very complete, from two-color machines to six-color machines, printing from 2 pages to 8 pages. Heidelberg started the development of the DI printer from the early 1990s and produced the GTO-DI printer. The Xerox company used the DocuColor 400 digital printer for the first time to interface with the press.
DI presses provide a choice for companies that want to replace (or supplement) color printers, and can bring more revenue to the company. Since DI printers can shorten the prepress preparation time necessary for traditional offset printing, some printers have found that DI printers are more competitive with toner-based systems for long-lived jobs, which greatly reduces costs. In addition, some printing companies use DI printers to print colored book covers and black and white printers to print text. DI presses can be directly plated on plate cylinders. This platemaking method offers several advantages over traditional platemaking or CTP workflows. First and foremost, the key benefit is the increased productivity and precision of printing because of traditional platemaking or CTP is made in the prepress process, and then the printing plate is installed on the printing press, which will inevitably produce some accuracy error, and the DI printing machine is to install the blank plate onto the plate cylinder and then image. The paper can be accurately positioned by the printer, and usually the first sheet can achieve the required accuracy.
In addition, the data of the plate image is interpreted during transmission to the printing press, which can automate the prepress preparation process, such as ink key setting. Because this automated process can accomplish multiple tasks, the prepress work done by the print operator in the past is reduced, and the prepress preparation time is greatly reduced. Another difference from traditional offset printing is that DI printing is a kind of waterless printing, which can reduce the cost of chemicals and other costs associated with traditional fountain solutions, and it is also good for the environment.
In general, any paper that can be used for conventional printing can be printed with a DI printer. This is very important. For example, if a customer needs to print a short version with a thick cardboard, the color printer cannot be completed. Combines offset and digital printing organically.
One of the main aspects that people hope to install a DI printer in a printing shop is that it organically combines offset printing and digital printing. Since the nature of today's business climate is a fast operational cycle, the use of a DI printer can meet this need. It can quickly print a multicolor book cover and then print with a toner-based printer. This workflow is very suitable for those personalized, variable data applications - each page's color area does not change, and personalized data, such as name and address are different on each page. Many printing companies take advantage of these two printing technologies in this area, providing high-quality, personalized color printing.
The American Printing Technology Foundation (GATF) conducted an in-depth investigation of the direct imaging printers. GATF issued a test form to the printers with direct imaging printers, allowing them to print 100 proofs of the test and submit them. Back to GATF. GATF analyzed the value of dot gain, image reproduction, ink density, print contrast and trapping, and reached the following conclusions:
â– The proof quality printed by the direct imaging printer is very close to the traditional proofs;
â– Because of the essential nature of the process of direct imaging printing, the pre-press proofreading process is crucial;
â– The number of screen lines for direct imaging printing is generally between 175 and 200 lpi.
â– General direct imaging press plate length between 25,000 and 100,000 sheets