常见假币形成方式区分方法研究

Preliminary Research on Distinction of Common Counterfeit Currency

认定假币形成方式是鉴别假币的首要任务。本文基于大量实际案件中收缴的假币票样,探究印刷版、打印版和复印版假币的区分方法,进一步通过比对喷墨、激光打印机打印样本,对相应假币的打印机品牌予以推断。采用VSC6000文检仪和立体显微镜观察,从图文特征、细节差异、墨点形成特征等,解析印刷、彩色打印、彩色复印这三类假币形成方式的差异;通过图文规则程度、色彩搭配等,区分单色印刷和四色印刷;通过墨点大小、堆积形态、墨点间距等特征,区分三类主要彩色喷墨打印机品牌(佳能、惠普、爱普生)的喷墨打印特征,进而推断喷墨打印版假币的具体品牌;通过对彩色激光打印机的跟踪暗码形状分析,区分不同品牌激光打印机,进而推断彩色激光打印版假币的品牌。通过比较,找到了区分印刷、打印、复印版假币的标志性特征,进而区分了单色印刷和四色印刷特征。应用该方法,分别认定了一起假币案件所缴获的假币票样具有爱普生彩色喷墨打印特征;另一起假币案件缴获的假币则具有富士施乐彩色激光打印特征。

Crimes of counterfeiting currency have been getting more complicated in recent years as there are more and more phony money printed by printing presses, laser printers, inkjet printer and the offset. The criminals have been improving the forging techniques by modifying their printing machines, printing ink, and paper in order to replicate the security features of RMB in great detail. Identification of the counterfeiting methods plays a significant role in providing clues for counterfeit crime investigation. In this paper, the counterfeit currency seized from the crime scene was studied together with samples printed by printing press, color printer and color copier. The research was also conducted to detect whether the counterfeits were printed by laser printer or inkjet printer and what brand of printer was used. A VSC6000 document examination workstation and stereo microscope were applied to observe the image-text characteristics, minor details of the counterfeits and to find how the ink dots were formed. With the differences detected, monochrome printing could be distinguished from four color printing in the aspects of the ordination of image-text, color matching, and the like. The major brands of color inkjet printer such as Canon, HP and Epson were identified by the size of dots, pattern of ink piled up, space between dots, and the others. By the shape and the tracking code of the color laser printers, the brand of the printer could be distinguished. Through a large amount of counterfeit currency, the characteristics of monochrome printing and four color printing were found, and therefore counterfeit currencies by printing presses, color printers and color copiers can be distinguished. The method has been applied in cases, where one counterfeit currency was identified to be printed by an Epson color inkjet printer and another counterfeit currency printed by a Fuji Xerox laser jet printer. There were other factors that might influence the analysis results, such as printer modification, the plug-in ink box used to improve the quality of the inkjet printing. The research needs to be further carried out to identify the brands of laser printer as its image-text is more complicated and the printer tracking code of laser printer is waiting to be understood clear on the counterfeited currency. The methods provided in this paper will be beneficial to people working on identification of counterfeit currency.