中文 2490 字 Digital printing Phil Green Digital printing is currently the most rapidly growing print sector, and one which is opening up new possibilities of short-run color work. It is also enabling entirely different relationships between the purchaser and supplier of printed products and making possible all kinds of new products. The conventional printing processes described earlier in this chapter are mature technologies. The technological development of these processes will continue, but will tend to deliver only incremental improvements in performance. Digital printing, by comparison, is still at an early stage in its development and will continue to develop rapidly, opening up new markets and making increasing inroads into the conventional process. In the medium term at least, it is highly unlikely that digital printing will entirely replace the conventional processes. This is for two fundamental reasons: The cost of colorants used makes unit prices too high to compete on longer runs; Modern printing equipment is designed around production economies of scale, with high speeds, large formats and inline processes such as folding and coating, and it will be some time before manufacturers build digital presses that can compete on high production volumes. The strength of digital printing is therefore largely in shorter print runs. However, the short-run market is expanding fast as print runs for all types of product are falling, and new products are made possible by integrated digital production. A direct cost comparison between digital and conventional printing may not be relevant in every case as digital printing can often provide a better solution to a communication problem, adding value and generating savings elsewhere in the production cycle, for example, in administration or distribution costs. This logic also applies to the print buyers when thinking of incorporating digital printing into their own operations, adding them to their existing design and prepress operations. To take a example in retailing, instore printing facilities linked to install and run than purchasing from external suppliers, but the marketing benefits may outweigh the additional costs. The point at which digital and conventional printing breaks even tends to be at a run length of around 1000 copies(more for black and white and less for color). Run lengths that do not fall automatically into the province of conventional or digital will be decided by the added value of the process: for digital printing this includes distributed printing and the ability to vary the image with each copy, while for conventional processes such as litho it will include the higher quality levels, the greater range of substrates that can be printed, and the availability of inline processes such as coating. Digital printing technologies Digital printers currently fall into four basic types: Page printers that print flat sheets of paper, usually in A4 format but sometimes up to A3 (these range from desktop printers to high -speed copier/printers like DocuTech, and include high-quality continuous tone printers used mostly for proofs and presentation materials); Large-format devices that print on continuous rolls, mainly for short-run posters; Overprinting heads for adding product codes (mainly for packaging) that are mounted onto conventional presses or finishing equipment, or on packaging lines; Reel-fed machines that print at speeds comparable to conventional printing presses. A digital printer has two fundamental components: a marking engine that transfers colorant to the paper, and a front-end that prepares the data used to drive the marking engine. The front end will include a RIP and a memory buffer. The page data is transferred directly to the front end without the need for films and plates, so there are large potential savings in costs. Because the digital printing device is driven by data and requires no plates, the image can be changed for each successive print. This variable image printing concept has great potential interest to publishers and advertisers who are interested in tailoring their communications more closely to what is known about their audience, often in conjunction with sophisticated marketing databases. Digital printing systems that operate at high speeds or high resolutions require dedicated front ends and large memory buffers, but low-end devices such as desktop printers can make use of software-based printer drivers that sit on the users host computer. The most widely-used technologies in marking engines are ink jet, laser and dye sublimation. Ink jet Ink jet printers deploy an array of nozzles to project ink droplets onto the paper surface. The nozzles are relatively cheap to produce, and wider arrays that can image a moving web of paper are currently in development. Ink jet print heads are found in all the types of digital printer listed earlier, and dominate the large-format and overprinting markets. They can print on the widest range of substrates (including cheaper grades such as part mechanicals). Laser Laser printers transfer toner to the paper surface electro-statically. An image is created on a photoconductive surface by adding or removing an electrical charge, and toner is attracted to the charged areas on this imaging surface (laser printers are perhaps more accurately known as electrostatic printers, since other energy sources such as electron beams can also be used to alter the conductive properties of the imaging surface). Most systems use dry toner powder, but liquid toner systems are also available and deliver much better print quality: smaller particle sizes yield higher print resolution, and gloss resins can be incorporated to make the finish more like that of a conventional print. Laser printers are mainly found in page printers and reel-fed printers. Dye sublimation Dye sublimation printers vaporize a waxy colorant and transfer it to the paper surface. The unit cost of prints made by this process are extremely high, and as a result its use is restricted largely to one-off prints for proofing or presentation purposes. Quality can be extremely high, comparable to a glossy photographic print. With all the digital printing systems there is a trade-off between resolution and speed. The more device pixels there are to be imaged on a page, the slower the print speed will be in pages per minute. Digital workflow-the mainstream of develop speedy development of digital processing and internet information exchange All-digital workflows are on their way. They will soon replace the traditional analogue imaging and reliable digital performance in graphical processing, proofing, output, and transfer. It will also enable no -film involved Computer-To-Plate system to take the lead. Multi-media documental output is no longer a dream anymore. Pre-press production line has becoming more integrated, professional and diversified. The main development trends of application software are openness, cross -platform functions, intelligence and standardization of documentation format. The implementation of digital workflow is the irresistible trend development in printing industry. Maturing printing technologies such as CopyDot scanning, digital proofing, computer-to-plate, and digital workflow gradually remove the obstacles to the implementation of digital technologies. Advanced output technology, together with intelligentization of digital workflow management will also improve the efficiency of digital printing operation. The digital technology process has almost replaced the traditional technology. The design and pictures can be transferred by network or through electronic medium. The corporation of pan-region, pan-country, pan-continent will be a common thing. We can offer the need, exchange information, remote proofing, and production tracking etc. The product can be designed in somewhere of the world, and printed in another place of the world. Direct-to-press One of the success stories of digital printing is Heidelbergs Quickmaster DI, which uses digital imaging on an otherwise conventional press design. Machines have been installed in a large number of bureau-type operations, and deliver many of the advantages of digital printing at the quality and cost associated with litho. Anew production model The traditional model of print production can be summarized as print a large enough quantity of a product to make unit costs economic, and then distribute to the end-user. Digital technologies make it possible to completely rethink the way in which visual communications are produced and distributed. Print-on-demand Because the amount of prepress work and press make-ready are minimal when compared with conventional printing, production costs are almost entirely variable, with a very small fixed element. This means that they become cost-effective to print copies as they are needed, instead of producing for stock. Distribute, then print Printed products are usually distributed over a wide geographical area, and it can sometimes be more cost-effective to distribute the pages in digital form for local reproduction. Distribute electronically For items whose function is information rather than marketing, end -users will often accept the end product in electronic form (on disc or CD): the pages can be printed individually as required. This allows the originator of the product to focus on its content instead of its reproduction. Alternatively, it may be possible to use an online distribution medium such as the World Wide Web, and create pages that are intended for viewing on screen rather than reproduced on paper. Variable image printing As each page is imaged separately, and there is no physical printing plate, it is possible to change some or all of the page with each successive print. This enables, for example, each communication to be personalized for its intended recipient, and groups of readers can then be targeted with information appropriate to their interests, their social background or their geographical location. 數字印刷 費爾 格林 數字印刷是當前印刷行業發展最快的部分。其中一個原因是他實現了彩色印刷的經濟性。他使得印刷品的消費者和供應商之間建立了完全不同的關系。 傳統印刷技術是相當成熟的技術，并將繼續進步，但將只傾向于只提供增值的改進。與傳統印刷相比 ，數字印刷剛剛起步，并將快速發展，開辟新的市場，不斷沖擊傳統印刷。 但是，最終在信息時代數字印刷不大可能取代整個傳統印刷。這有兩個根本的原因： 1.單張印品所使用色料（油墨）的價格較長版活高出很多。 2.現代印刷設備是圍繞印刷產品的經濟性而設計的，要求速度高 .規格大 .能在線進行折頁 .涂布等。在制造商生產出可以在線完成大批量產品的數字印刷機前，傳統印刷技術將長期存在。 數字印刷技術的優勢在于短版活。然而短版市場快速擴張，更如能印刷各種印刷品的印刷機快速減少，新的產品將通過與數字印刷技術的結合而產生。 一個直接 的消費變化并不是與任何情況都相關的，比如數字印刷技術對于連接問題提供了一種更好的解決方法。在生產的整個過程中，有些地方增加了成本，有些地方則節約成本。例如在管理和拆版的費用。當考慮要將數字印刷作為其操作的一部分，實現在線設計和印前處理時，這種邏輯也被印刷機購買者所采用。拿零售商為例，必將出現印刷設備與核心價格及市場數據庫聯系起來，這樣就可以在短時間內生產出新賣點的材料進行安裝運行，而不是從其他供應商處購買，市場利潤將可能超過傳統工藝的成本。 數字印刷的賣點在于生產 1000 個左右印品（黑白地較多，彩色少）。印 數由印刷流程的附加費用決定：如數字印刷中就包括分類印刷和個性印刷。而對于傳統工藝如膠印則包括較高質量要求，大量片基需求，在線涂布等。 數字印刷技術 數字印刷機通常有四種類型： 單張紙印刷機，幅面通常為 A4，也有的達到 A3（此范圍從桌面打印機到高速印刷機如 DocuTech,包括通常用來打樣和印刷圖象稿件的高質量的連續調印刷機） 卷筒紙印刷機等大型設備，主要為速遞服務者所用。 套加印設備，用于傳統印刷或作為最后一道工序，給印刷品（通常為包裝印刷）加印代碼。 卷筒紙印刷機，印速可與傳統印刷機相比。 一臺數字印刷 機由兩部分組成：一套印刷裝置，將油墨轉移到紙張上；一套印前系統，為印刷提供數據資料。該印 前系統包括 RIP 和記憶緩沖器。數據頁面直接傳輸到印前系統，不需要菲林和印版，因此省卻了大量的印前費用。 由于數字印刷機用數字形式取代了印版，在連續印刷中就可以改變圖象。這種“可變數據”印刷的概念對于印刷商和廣告業者有著潛在的影響，他們經常在生產中使用高度復雜的市場數據庫，針對人們的興趣及時對圖文進行修改。 高速或高分辨率的數字印刷系統配有先進的印前裝置和大容量的記憶緩沖器。而低檔設備如桌面打印機可以利用電腦軟件進行工作。 現在應用最廣泛的技術是噴墨打印，激光打印和染料升華技術。 噴墨技術 噴墨打印機配置了一排噴嘴，將墨滴噴射到紙張表面。制造噴嘴是相當便宜的，而能夠連續繪圖的寬排噴嘴也在不斷發展中。很早以前，各種型號的噴墨打印機出現并系列化，主宰著套印市場，而且他們的承印物范圍是最廣泛的。 激光技術 激光打印機以帶電的方式將色劑轉移到紙張表面。通過增加或轉移電荷使圖象呈現在一光導面上，帶相反電荷的色料被