Unique traditional plate-making technology CTcP

Since Drupa in 1995, the computer-to-plate technology CTPlate has developed rapidly and has been rapidly put into use in the field of publishing and printing. This has played an important role in the digitalization and integration of prepress processing and platemaking. Among the computer-to-plate technologies, the development of new types of plates and direct plate-making equipment has taken a pivotal position. At present, the mainstream of CTPlate technology still focuses on the thermal printing plate technology and infrared laser recording equipment with a wavelength of 830 nm/1064 nm. Thermal plate has excellent dot reproduction quality and can be exempt from post-processing. It does have excellent quality. It is a promising platemaking technology in today's and the future. However, people have not forgotten the traditional pre-coated version (PS version), hoping that it can "make new achievements" in the CTPlate trend. The BasysPrint company in Germany and Purup-Eskofot company in Denmark respectively introduced their own traditional computer-to-plate (CTcP=ComputerToconventionalPlate) devices, opening up new prospects for the application of traditional PS versions. Figure 1 I. BasysPrint's UV-Setter direct plate-making output machine 1. UV-Setter direct-plate-making output machine basic performance: BasysPrint company developed and produced three models of direct plate-making output: UV-Setter57 type, UV-Setter710 type and UV _Setter1116 type. All three models are flat structures. The three largest recording formats are different: UV-Setter57 is 610mm×660mm, 710 is 820mm×1120mm, and UV-Setter1116 is 1350mm×1700mm. All three models have 900dpi, 1500dpi, and 2540dpi three-speed recording resolutions. The UV-Setter plate printer uses an ultraviolet light source to record the exposure of a conventional PS plate. The wavelength range of the light source is 360-450 nm. Figure 1 shows the appearance of the UV-Setter direct plate output machine. 2. The plate-recording technology of the UV-Setter direct plate-setter output machine: The recording head of the output machine is the key to its technology. It adopts the "Digital Micromirror Device" (DMD=Digital Micromirror Device) to image the recording exposure dot matrix on the printing plate. The surface exposes the PS plate. Move the recording heads row by row or column by column to record the entire printing plate in its entirety. Figure 2 Figure 3 As shown in Figure 2 and Figure 3, DMD is a digital imaging component designed and manufactured by Texas Instruments. It processes hundreds of thousands to one million micromirrors on approximately 20 x 20 mm2 silicon wafers. The micromirrors are arranged in rows and columns. Each micromirror can be deflected by +10°/−10° under the control of a binary 0/1 digital signal. FIG. 4 shows the structure of the DMD: the surface of the micromirror is coated with an aluminum layer, and each micromirror has a CMOS cell underneath. The electrostatic attraction between the CMOS and the micromirror deflects the micromirror, and the signal voltages of different polarities cause the micromirror to deflect in different directions, and the light radiated on the aluminum surface of the micromirror is deflected at different angles accordingly. The 0/1 digital signal is used to control the different deflection directions of each micro-mirror, so that the position to be imaged becomes a "bright spot" without the need for the imaging position to become a "dark spot", and the digital control of imaging can be achieved. (See Figure 5.) Figure 4 We know that in the prepress processing stage, text, graphics, and images are processed and combined into printed layout information, interpreted and rasterized by RIP to obtain 0/1 signals that can be recorded. Each bit of this binary signal corresponds to one recording point on the plate. In the case of an offset printing plate, only the "non-recording" and "recording" states correspond to the 0/1 signal. Fig. 5 As shown in Fig. 6, the light emitted by the ultraviolet light source is focused by multiple mirrors and objective lenses to reach the digital micromirror device DMD. At the same time, the plate recording signals obtained through the RIP process are sent to the DMD in matrix rows and columns. On the DMD, micromirrors corresponding to points that do not need to be recorded are biased to one side, and the micromirror corresponding to the point to be recorded is biased to the other side, enters a converging mirror, and images the light of the recording matrix on the PS plate. . Fig. 7 is a microscopic image of the obtained dot, and the edge sharpness of the dot is higher. Figure 6 2. Dicon plate printer output from Purup-Eskofot, Denmark: 1.Dicon direct plate output machine basic performance: Dicon is a flat type plate printing equipment, its maximum format is 1125 × 825mm, recording resolution is 1270 and 2540dpi. The machine uses ultraviolet light to expose the plates. It is said that its recording speed reaches 30 to 50 full-print plates per hour at a recording resolution of 2540 dpi. Figure 8 shows its appearance. Figure 7 2.Dicon's plate-recording technology for the direct plate-making machine: Dicon uses a high-power mercury arc lamp to generate ultraviolet light, which is transmitted through the fiber bundle to a LightSwitchingArray. The light switch array consists of a large number of optical switches. Each light switch can form a 20-micron recording spot, and its on/off is controlled by the recorded digital signal. The light switch array LSA is arranged in one row, and its width coincides with the maximum width of the printing plate, so that one full row of pixels can be exposed and recorded at a time. When recording a plate, the recording head formed by the LSA is stationary, and the printing plate is moved accurately and stably. The moving speed can reach 10 mm/sec. It takes only about 80 seconds to record and expose the 825 mm wide printing plate. Fig. 9 shows the structure of the light switch array. Fig. 10 shows the principle of recording and exposing the printing plate by Dicon. Figure 8 3. Advantages of traditional PS plate computer direct platemaking: For the technical implementation means, the above two companies developed and produced computer direct plate making equipment with their own characteristics, but their common features are: the use of the wavelength range of 360 ~ 450nm UV light source implementation of the traditional PS version of the exposure record, the advantage is: Figure 9 1. Can make full use of the existing traditional PS version of the resource. This is more appropriate for the current production and sales status of the traditional PS version in China. 2. Reduce the printing plate cost of the CTPlate process. At present, the development and production of domestic CTPlate thermal printing plates is still in its infancy. CTPlate printing plates still need to be imported to a large extent, and the cost is relatively high. The traditional PS version plate-making equipment joins the plate-making process flow, which has a great advantage in printing plate cost. 3. The process requirements can be met from the image quality and production efficiency of the printing plate network. Figure 10 From the above three perspectives, the traditional plate-making CTcP should have a certain living space in China at present. It is one of the approaches that can be considered for printing units that expect to enter digital prepress processing and platemaking. It would be better if domestic manufacturers could provide such equipment. In the all-digital trend of pre-press processing and plate making, CTcP can make its due contribution to the overall popularization of computer-to-plate.