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The secret of CTP technology: How to make every printing plate accurate and flawless?
With the rapid development of printing technology, computer-to-plate (CTP) technology has gradually become the core of modern printing process. This technology enables images created in desktop publishing applications to be output directly to printed pages, eliminating the computer-to-film (CTF) process that was previously required. The introduction of CTP technology marks an important turning point in the printing industry. While improving printing accuracy, it also reduces costs and time for the printing industry.
CTP Technology Overview
CTP methods vary depending on the type of imaging device build and the light source it uses, and there are three main types: internal drum, external drum, and flatbed imagers. These three structures each have their own characteristics and can adapt to different printing needs.
CTP technology can directly convert digital images into printing plates, which makes the production process faster and more accurate.
Internal drum imager
In an internal drum imager, the printing plate is placed inside a cylinder and the imaging head moves along the axis of the cylinder to expose the printing plate. Although this design makes it more difficult to use multiple lasers simultaneously, the advantage of a single laser is that it can provide a uniform beam intensity.
External drum imager
The design of the external drum imager allows the printing plate to revolve around a rotating cylinder, and the imaging head can move along the cylinder to focus the laser. This simple structure facilitates the parallel use of multiple imaging heads, thus The time required to expose the entire printing plate is reduced.Flat-bed imager
In a flat-panel imager, a laser beam is reflected by a rotating polygonal mirror onto a fixed flat plate, reproducing the image line by line. This setup makes the laser beam less accurate at the edge of the printing plate and is therefore usually used for smaller formats or production with lower quality requirements.
Comparison of various printed editions
Photopolymer Printing Plates
The photosensitivity of photopolymer printing plates ranges from 380 nm to 550 nm, and the low laser energy required for exposure is 30 to 100 μJ/cm2, with a minimum output of 300,000 prints.
Silver halide printing plate
Silver halide printing plates have a light sensitivity range of 400 nm to 700 nm, require very low laser energy for exposure, only 1 to 2 μJ/cm2, and can achieve a resolution of 450 LPI.
Thermal printing plate
Thermal printing plates have a light sensitivity range of 830 nm to 1,070 nm, require laser energies ranging from 70 to 200 mJ/cm2, and can achieve print runs of up to 500,000.
During the printing process, the use of CTP technology has significantly improved the accuracy and efficiency of printing, and has gradually replaced traditional methods.
Advantages and Challenges of CTP
CTP technology has many advantages over traditional plate-making methods, including improved image clarity and detail. The accuracy of a CTP system can generally reach ±2%, and compared with traditional methods, CTP has shown higher efficiency in both time and cost of printing plate production.
However, CTP technology also has certain limitations. Since CTP is limited to digital format, this means that the basis and layout of all printed materials must be in digital format. If a printing plate is damaged during the production process, the entire printing plate will need to be remade.
Recently, some companies have been committed to further developing CTP technology, gradually widening the gap between it and various analog printing technologies, covering more detailed gradient effects and less dot growth. These innovations not only improve printing quality, but also expand printing possibilities.
So, how will future printing technology evolve to meet the demand for higher precision and quality?
