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UV-Printer: UV-Lamps or UV-LEDs?

Russian advertising market has been increasingly developing and over comparatively short period of its existence (slightly more than 15 years) the market has lived through several technological revolutions. Scientific and technological progress is evident: producers make efforts to reduce prime cost, implementing the latest know-how and optimizing production; market participants reap the fruit of the progress, getting used to the increased competition.

Sweeping development of the broadside printing market in 2002 and 2003 (the market growth dynamics could reach 100% growth per year) resulted in the fact, that the cost of printing for end user dropped many times. Taking into account steady reduction of the printers’ prices and, as a consequence, growth of the printers’ number on the territory of Russia, many advertising agencies got a chance not to pass their orders for subcontract execution but to print the orders themselves. Several years ago the problem of market saturation was brought up by some experts. The market saturation, as we consider it, is approaching, and it will bring slowdown of the market growth on the one hand, and decrease of economic efficiency on the other hand. General situation on the advertising market also contributes to that. Growth of the total advertising market slowed down dramatically, so many advertising producers, which are constantly seeking for an opportunity to invest spare funds in the development of their own business, began to pay more attention to the related branches. The first UV-printer, which appeared in Russia in 2003, ushered in the new era of advertising business, or we even can say the new era of printing business. The equipment, which can print on any type of surfaces, attracted considerable attention. The given equipment actually opened infinite number of the market niches.

At the moment, quite a few advertising agencies not only know what a UV-printer is but also realize that UV-printing process is made with curable ink. Such subjects were widely promoted and highlighted with the utmost clarity by all available means of communication: exhibitions, magazine articles, photo materials on the sites of the organizations, supplying such type of equipment, and you can also find videos with the presentation of the UV-printing process in the Internet.

The UV-printing process was widely discussed in the specialized editions and in the Internet, but there were and there are some subjects, which have not been touched upon by the producers of the UV-printers. On of such subjects is an emission source, which forms the basis of the said printers. Till recently the UV-lamp was the only source to cure ink, and it did not promote to the rapid development and spread of the UV-technology. Moreover, it slowed down the process of the UV-introduction into the broad masses. As we have already stated, the market of the advertising production is developing swiftly enough, and LEDs start replacing UV-lamps. Some experts of both Russian and foreign markets of advertising production consider that LEDs are really doomed to success. However, which is to choose: time-proved UV-lamps or comparatively new technology of the UV-LEDs?!

Brief information on the history of the UV-printing

The first UV-ink-jet printer appeared in 2000 (Durst Rho160). The UV-technology came to Russia a bit later. The main problems were connected with ink. The problems have existed till the beginning of 2003 when “Sericol” and “Inca” companies produced “Uvijet” series, thereby breaking through in the flexibility and increasing range of the UV-ink colors. The first UV-printer appeared in Russia only in the summer of 2003 (“Inca Eagle” of “WeR.Signs”). The first “NUR Tempo” UV-printer was demonstrated at the end of 2003 at the “REKLAMA-2003” exhibition.

Brief information on the UV-LED history in the ink-jet technologies

From the very outset of the UV-printers’ development producers tried to find alternative replacement of the UV-lamps. The UV-LEDs were the only solution at that moment, but a very low power (milliwatts) and a high price of such UV-LEDs was a problem. The first UV-LED-based printer was presented at the FESPA-2006 exhibition. That was Luscher JetPrint 3530 UV-printer (a consumer had to pay 100,000 euros for one module of the UV-LEDs). As the saying goes “you must spoil before you spin”, the printer proved to be not efficient, and the UV-LEDs were replaced by the UV-lamps. After that, the “Inca Digital” company decided to repeat an experiment with the development of the UV-LED-based printer, and that resulted in the production of the new printer version – Spyder 150. By now, only 12 printers of the same type have been sold all over the world. The UV-LEDs are also used in the “Daytona T600UV” hybrid printer of “Raster Printers” company, which uses both the UV-lamp and the UV-LEDs in its printers. They explain joint usage of the UV-lamps and UV-LEDs by a low emitting power of the LEDs, which is not sufficient to cure the ink. The latest development – NEO UV-LED printer of the Russian Company “SUN”- solved a number of problems, which have not been solved by its predecessors.

Terms

UV (UV, ultra violet) is an ultraviolet emission with the wave length from 100 to 400 nanometers from the emitting source (the most known source of ultraviolet emission is the sun).

The UV-lamp is a source of emission, which is required to obtain the wave of the preset length. An average life cycle is from 600 to 1500 hours. The warm-up period is 2-5 minutes, depending on the type of the lamp. Emission spectrum is only 30% of the required spectrum. The following things make it difficult to obtain high power: requirement of high-frequency power source, considerable heat release, tiny percentage of the efficiency coefficient, ozone release. Advantages, available at the moment: this is the most powerful source of the UV-emission.

The UV-LEDs are the main source of stable emission. An average life cycle is from 40,000 to 100,000 hours. The warm-up period is measured in fractions of seconds. Emission spectrum is fixed according to the selected range. Shortcomings: not very high power of one light emitting diode, high price of the light emitting diodes. Advantages: very high percentage of the efficiency coefficient, lower power consumption, long run time, minimum heat release even under continuous running.

The UV-printing is a process of polymerizing UV- curable ink.

The UV-lamp was the first …

As may be seen from the history, the UV-printing originally passed through a number of complicated stages in the digital ink-jet industry. First, it was impossible to print on some media and the color range was poor. As LED technologies were not sufficiently developed, producers of the equipment chose the UV-lamps as a unique source of emission. If there is no alternative, one has to shut his eyes to such drawbacks as high power consumption, high lamp heating and others, not to mention impossibility to print on thin media or media sensitive to heating (such as thin two-millimeter plastic or foam plastic). Rapid development of the UV-printing technology was hampered not only by the UV-lamp but also by the absence of the curable ink, which, unfortunately, appeared only in 2003. The ink might be, to some extent, the main hindrance in the development of the new stage of the UV-printing – introduction of the UV-LEDs.

The first attempts to use the light emitting diodes

There were some attempts to introduce the light emitting diodes, and not only in the full color printing. Don MacCallum, an engineer of “XAAR” company, had developed mono color printers to print books for the blind, before he joined “XAAR” company. Thanks to the fact, that UV-curable ink becomes bossy after polymerization, the UV-printing appeared to be the only solution for developing printers of similar category. Don told that at the Cambridge University he spent a lot of time investigating both the UV-lamps and UV-LEDs. The result was poor, because the light emitting diodes were very low-powered and they could not cure the ink, whereas the UV-lamps cured perfectly well, but if the emitter’s power was chosen incorrectly, the paper turned yellow and warped after printing.

Another expert was Derrick Mowles, a specialist of “Dimatix Inc.” company (Spectra Division), who previously had been working as a technical expert in the “SunChemical” company. He told that the light emitting diodes have already been investigated for a long period by the companies, producing full color UV-printers. Though such testing was not advertised in the press, the information became available in the narrow circles. The testing showed that the LED’s’ emission can cure only an upper layer of the ink by means of repeated runs, whereas the UV-lamp cured the same layer within one run.

New performance capabilities of the light emitting diodes (LEDs)

The main problem, more likely, lies not only in quite serious drawbacks of the UV-lamp but in the fact that you can not print on many types of materials. A thin film will warp under considerable amount of heat, emitted by the UV-lamp. The paper turns yellow during printing. Many thin materials warp after printing and it is not possible to use them.

For example, such material as foam plastic can not be used with the printers based on the UV-lamps. The same can be said about thin plastic - 1-2 mm thick, not to mention various types of films, used in the printing industry (flexographic printing and serigraphy). So, the companies with the UV-lamp-based printers had to refuse some orders, especially the orders for which customers brought their materials to print on (sometimes only 20% of the customers’ materials could be used).

Table of distinctions (Lamp vs LED)

The main thing is the ink

It is evident that all UV-LEDs’ parameters are better than parameters of the UV- lamps, including difference in efficiency coefficients and life cycles (difference in these parameters is the most evident). If it is remembered that: the UV-lamps consume large amount of power during operation, the cost of one UV-lamp is about 600-1000 dollars, the lamp must be replaced every 3-6 months (according to the number of the worked hours per month), it is impossible to understand why the UV-lamp printing is still profitable. Nevertheless, according to statistics, almost 99% of producers of the broadside flatbed UV-printers choose the lamps as the main source of emission (ink curing). Perhaps, the major cause of a progress slowdown lies in the fact that producers of the equipment do not have special ink for the UV-light emitting diodes. At the same time, ink manufacturers can not see ink consumption market for the light emitting diodes (because such market does not exist), so they do not invest money in the development of formulas and chemical technologies for the new emission sources. As far as we know, some companies produce printers and the other companies develop ink. They are different companies with different goals and tasks, which do not always coincide in real life.

In place of conclusion

The answer to the question, which was raised at the beginning of the article, is absolutely evident. The light emitting diodes proved preference of their technology in all parameters. For many people economic expediency must probably be a principal criterion for this or that technology, and in this connection you will have the following: using the UV-lamps within the established life cycle of the light emitting diodes (two lamps for bidirectional printing) you will have to replace the lamp more than 40 times, that will amount to $50,000.