影響平凸版底紋印刷品質因素之分析

Factors Affecting Printing Quality of Background Images On Dry-Offset Presses

謝東憲(HSIEH TONG-HSIEN)

指導教授 ： 吳紹起 ； 王貴川

國立臺灣師範大學/科技學院/圖文傳播學系/碩士(2002年)

摘要

平凸版底紋印刷圖像主要是由不同形狀或大小的點、精密細線條及色塊所構成，其防止彩色掃瞄影印圖紋，可以有效遏阻一般電腦掃瞄列印對安全文件的偽造複製。根據美國凹版印刷局長Ferguson指出：大約有50%以上的美鈔偽造案例，都是利用彩色掃瞄、複印機等設備來複製的。所以在2003年即將發行的新版美鈔中，特新增有八色平凸版底紋圖案，以強化鈔券的防偽效能。惟平凸版底紋印刷過程尚無建立標準模式來控制色彩品質的穩定性，作業人員多以主觀經驗作判斷比較。因此本研究目的是希望透過實驗，針對平凸版底紋印刷過程中造成網點擴大及細線條線幅粗化的因素進行探討，並發展出一套控制網點擴大和線幅粗化的模式，以增進印刷品質的穩定性，俾提供有價證券印刷業者參考。本研究採23多因子設計＜共3個因子，每個因子均有2個水準＞，探討平凸版底紋印刷時，印刷速度、觸版輥與印版滾筒間的壓力以及吃墨輥供墨量等三個因子對滿版濃度、印刷對比、網點擴大及線幅粗化等的影響。23多因子分析可得8種不同的處理組合，實驗順序係由Minitab統計軟體之隨機選取決定；使色樣濃度達標準規範下之每組各印製100份印樣，並將印樣分別從1至100予以編號，從中選取偶數號印樣分別進行測量；亦即每個處理組合需分別測量50份印樣。每份印樣分別以X-Rite418濃度計來測量滿版濃度、印刷對比、25%、50%及75%網點面積；以PAKA 100放大鏡來測量水平暨垂直方向20μm、40μm及80μm等線幅粗化情形。經統計分析與討論，本研究之重要結果與發現：1.吃墨輥之供墨量和觸版輥與印版滾筒間的壓力等兩因子的主效應，以及印刷速度和觸版輥與印版滾筒間的壓力之交互作用，幾乎對所有的依變項均有非常顯著的影響。2.研究發現當印刷速度為6,000st/hr、吃墨輥之供墨量在15mm、觸版輥與印版滾筒間的壓力為3.5mm時，可得最大的印刷對比值、以及最好的網點擴大及線幅粗化控制，是平凸版底紋印刷的最佳操作模式。3. 當印刷速度為7,000st/hr，吃墨輥之供墨量為22mm，觸版輥與印版輥筒之間的壓力為3.5mm時，可得到滿版濃度的最大值。

關鍵字

平凸版印刷 ； 底紋 ； 實驗設計

並列摘要

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.

並列關鍵字

Dry-Offset Printing ； Background Images ； Design of Experiments

參考文獻

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