The latest laser source of the computer-to-platemaker CTP

Foreword:

The computer-to-plate machines have been exhibited for the first time since the 1995 Drupa International Printing Exhibition, so that the Drupa 2000 has been used in commercial applications, and the global printing market is responding to this new technology with a high growth rate. The installed capacity in the global market has exceeded 6,500 units, although the Asian market was later started, there are more than 30 installed units in Hong Kong and China. However, there are a large number of operators who, although interested in investing, are still looking at the evolution of technology to find the most suitable model for their own. The development of CTP machines is also changing with each passing day. Over the past few years, new models and new technologies have been introduced. There are also many types of models that are eliminated. Useful internal drums and external drums are also platform-style. With light sources, almost all Wavelength lasers have all been used on CTPs, but today it seems that they have been integrated into two camps. One is a silver salt system using visible lasers, and the other is a thermal plate system using infrared lasers. There are advantages and disadvantages, each has its supporters, and even sparked controversy on the internationally acclaimed Seybold, but it is hard to say which system will become the mainstream in the future. For Agfa, the two systems are balanced development to meet different customers. Demand.

If manufacturers of various systems are concerned, before the Drupa 2000 exhibited, it seems that the manufacturers of the heat-sensitive system predominated, but Drupa 2000 had a number of manufacturers introduced new models using the violet laser, it seems that two The party camp is evenly matched. In view of this, Mr. Kurt Wolf, a senior correspondent in Europe of Seybold, paid special visits to various suppliers and users to understand the development and characteristics of violet lasers, and explained why violet lasers can emerge after Drupa. This article is based on Mr. Wolf's research report and the company's product information, to introduce to readers the characteristics of purple laser.

Violet laser is not 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.

1. The origin and development of violet laser:

As of September last year, there was only one supplier supplying violet laser diodes in the world. This is a Japanese company “Nichia”. Nichia was founded in 1998. The original research and development concept was to develop infrared and red that are already quite common on the market. Diode lasers with shorter laser diode wavelengths are designed to further increase the storage capacity of optical discs. Nichia was the first to successfully develop a violet laser with a wavelength of 391-420nm. Since the shorter wavelength laser has a smaller laser spot, it can be written under the same density of storage media with a better optical lens. More information.

The following table shows the laser head wavelength used by different optical disc formats, and the relationship with the storage capacity:

Optical Media Laser Type and Wavelength Storage Capacity (Single-sided)

CD, CD-R, CD-RW 780nm Infrared Diode Laser 650 MB

Home DVD 640nm Red Diode Laser 4.7 GB

Professional DVR (in development) 400nm violet laser diode 30 GB

Since the production and application of Nichia's violet laser diodes have not yet been universally popularized, the diodes are still selling at a high price, but they are still not universally available. However, this price is relatively affordable compared to the CTPs of industrial products. Therefore, the price is currently purple. The most widely used field of laser diodes is the CTP industry.

Nichia said that in the next five years, the price of violet laser diodes can be reduced to acceptable levels for home appliances.

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, 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.

Stable quality, further enhance the drum 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 speed defects, so replace The cost of new purple lasers 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

It is also often mistaken for the short life of the violet laser. In fact, it is also misdirected 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 the argon gas. Lasers, therefore, cannot be controlled in a circuit-controlled mode to switch on and off, but instead use a constant-bright tube and then use lens deflection to control the laser spot, so the average lifetime is only about 2.5 years, and the effective production hours are 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. Application Status of Purple Laser to CTP

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. (See the figure below)

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.

6. Purple laser CTP is good or thermal CTP is good

When operators invest in CTP, there are still many factors that are actually considered. The thermal CTP system is also continuously improving. Because each has its own advantages that cannot be replaced, it also exists in the market to meet the needs of different customers. , so basically there is no absolute best CTP system, but only the system that best suits your operating environment. However, due to the many advantages of violet lasers, this product has achieved market acceptance at the launch of Drupa 2000, and has created an impressive sales volume. We also hope that the development of science and technology will continue to bring more benefits and business space to the printing industry.