Computer-to-plate machines have been exhibited for the first time since the 1995 Drupa International Printing Exhibition. The global printing market is welcoming this new technology with a high growth rate. The development of CTP machines is also changing with each passing day. New models have been introduced over the past few years. With the advent of new technologies, there are also a number of models that are eliminated, useful internal drums, external drums, and platforms. In terms of light sources, almost all wavelengths of laser light have been used on CTPs, but the evolution to today seems to have been integrated into two camps. One is a silver-salt version system using visible light lasers, and the other is the use of infrared laser heat. The Minyi system, two systems that once caused controversy on the internationally renowned Seybold. In view of this, the author has learned about the development and characteristics of violet lasers through various channels, and hopes to share them with readers.

1, the origin and development of violet laser

The first thing to clarify is that violet lasers are not argon lasers, and many people have been mistaken for violet lasers that are the same argon lasers that were a decade old. In fact, this is a completely different type of laser technology. The argon laser is an early gas laser that is bulky and requires a large amount of energy to excite argon to produce a blue laser. The laser tube has a short lifetime and a high selling price. The early roller scanners used argon lasers. Purple laser uses the latest laser diodes and solid-state purple lasers, which consumes very low energy, has a long life and is stable. So violet laser is not only outdated technology, but the latest technology.

2, the advantages of violet laser

High-resolution

Due to the smaller laser spot generated by the short wavelength, it can provide higher resolution and also represent higher printing quality, and the output resolution can reach 250 l/inch.

Small size, fast speed

Because of the smaller laser spot generated by the short wavelength, the volume of the reflective lens of the laser head can be reduced, and the smaller laser head volume means that the rotational speed can be increased. With the high-sensitivity silver salt plate, the laser head speed can be as high as one minute. At 55,000 revolutions, the laser sweep speed is 5,078 km/hr if converted to the circumference of the inner drum, which is equivalent to 4.26 times the speed of sound. At such a fast rate, even a single laser beam can produce 22 full-print plates per hour (1030800mm/2400dpi), which is the highest output on the market today.

Bright yellow safety light can be used

Thanks to the use of a purple light source and a corresponding light-sensitive material, it is possible to operate under a bright yellow safety light, approaching a bright room operation, and increasing ease of use.

Quality and stability, to further enhance internal drum type performance

The laser diode light source is stable and the laser spot is strong, which can produce high-quality dots and improve the printing quality. Although the current cost of the violet laser is still high, because the inner drum model only uses a single laser, the total cost of the CTP is limited, but the outer drum model is often used because it is limited by the rotational speed of the plate cylinder. Laser beam to compensate for the speed of the defects, so the cost of replacing the new purple laser has become relatively significant. Therefore, at present, the CTP on the market is the first to use the violet laser in the internal drum type.

Easy maintenance and quick replacement

Due to its small size and high degree of modularity, the violet laser diodes are easier to maintain and replace, reducing maintenance hours and increasing the number of hours of production.

3, the life of violet laser

Frequently someone misunderstands the short life of the violet laser. In fact, it is also misguided by the argon laser because the working principle of the argon laser is that the laser tube is constantly lit, because it requires a large amount of activation energy to excite argon to generate laser light. Therefore, it is impossible to control the switch on and off in a circuit control mode. Instead, the lens is used to control the laser point using a constant light tube. Therefore, the average lifetime is only about 2.5 years, and the effective production time is also very short.
However, the violet laser is totally different. Because it is a diode, it consumes very little energy. Therefore, when it is not in operation (starting but no exposure), the laser is not bright, and only the laser light is exposed, so it can effectively extend the laser lifetime. Currently, the lifespan of violet laser diodes is about 3,000 hours. Take the 1030 x 770 version as an example, 100 plates are produced each day, 250 days a year, and 3,000 hours are equivalent to 3.5 years. This is a good return on investment. No worse than infrared diode lasers.

4, purple laser in the application of CTP status

At present, there are manufacturers of violet lasers used in CTP platesetters such as Agfa, Barco Graphics, Krause Biagosch, and Purup-Eskofot. The plates used are the silver salt plates. The current suppliers of silver salt plates include Agfa and Mitsubishi Paper. Since the silver salt plate is a mature and stable technology, and is currently the most widely used digital version in the world, its high-resolution characteristics can just take advantage of the short wavelength of the violet laser, so the output resolution can reach 250 l/inch, plus The high-sensitivity features of the silver plated version require only 2.5 μjoules of energy to be sensitized, while the 2.5 μjoule energy is equivalent to only 5% of the output power of the 5 mW laser head produced by TuiOptics. Laser matching silver salt version is a temporary choice, and the perfect match is not an exaggeration.

5, the future development of violet laser

Due to the many advantages of violet lasers, several well-known home appliances and semiconductor manufacturers have successively invested in research and development, such as Sony, Sharp, Sanyo, etc., and many more input means that the future products must be more diversified, and more advantages will be developed. , And the price will be reduced due to competition and popularity, with the current development of violet laser is taking off, will not be eliminated in the short term. At present, in the application of CTP, Nichia is also working hard to increase the energy of the laser. The goal is to produce a 30mW (now 5W) product that is used for plates other than the silver salt version, such as the Photopolymer version. Six times the output energy, so it is still technically difficult.