| Summary: | 碩士 === 國立臺灣師範大學 === 圖文傳播學系 === 91 === The background images of Dry-Offset printing were mostly composed of different sizes and shapes of dots, micro lines and color patches. Defensible copy pattern of background images would be prevented from the anti forgery of color scan and photocopy from security documents. According to Ferguson’s reported：Over 50% of forged notes cases of the U.S. currency were made from color scan and photocopy. The U.S. government had decided to increase eight colors background images of Dry-Offset Printing into the new banknotes in the 2003 New U.S. dollars publishing plan for reinforcing its securities functions. However, the background images of Dry-Offset presses never had the manipulative standard model being established for controlling the printing quality. The press operators usually make quality judgment based upon their practical experiences, even though this kind of operation method will be affecting the printing quality maintenances. Thus, the purpose of this research was to explore Dot Gain(DG) and Lines Enlarge(LE) two factors affecting printing quality, to develop a model for controlling the printing process conditions of the Dot gain and Lines enlarge, to create a stable controlling procedure for printing quality, and to provide a reference for security documents printer. This study used a 23 factorials design（3 factors, each at only 2 levels）, which presented the effect of Speed, Ink Flow, and Pressure on the response of Solid Ink Density(SID), Print Contrast(PC), DG, and LE etc. The 23 factorials design had eight treatments combination. The full model experiments order were randomized, and decided by Minitab software. Each treatment printed 100 proofing sheets on a properly terms of printed and selected even number sheets from proofing sheets to be measured. Using X-Rite 418 and PAKA 100 magnifying glass instruments to measured dependent variables of the study. By way of analyzed factorials, discussed, and results indicated that：1. Two main effect of Ink Flow and Pressure, and Speed & Pressure interaction almost had signified effects with regarding to every dependent variables. 2. The best printing operator model was when Speed＝6,000 st/hr, Ink Flow＝15mm, and Pressure＝3.5mm. DG and LE had a better control, and PC would appear the max value. 3. It had a max value of SID when Speed＝6,000 st/hr, Ink Flow＝15mm, and Pressure＝3.5mm.
|
|---|
