2024 Volume 29 Issue 2 Pages 155-168
An electrostatic detection device (EDD) is a device that uses electrostatic charge to detect invisible indented writing impressions left on a paper surface. In this study, the following four types of experiments for the phenomena of the EDD detection and the possible applications other than detecting the indented writing impressions were conducted and discussed. First, the EDD detections were examined with various color materials on a paper: marker ink, whiteboard marker ink, vermillion inkpad ink, and inkjet printer ink. Second, visualization of the characters without indentations was attempted by EDD. Third, the EDD detections were examined with sweat, oils and fats. Fourth, visualization of obliterated and tampered characters or patterns of documents was attempted by EDD.
The results showed that the adhesion of toner onto the Mylar film differed depending on the color material component: toner occasionally adhered tracing only the outline as well as the whole face of characters. This suggested that the chemical properties of the color material components affected the detection results. In addition, characters without indentations were visualized from the table top of EDD, which indicated the EDD can detect color materials and triboelectric charge caused by writing. This finding suggested that the phenomenon that the EDD detects fingerprint is due to its detection of sebum transferred to the paper. Furthermore, the EDD succeeded in visualizing obliterated and tampered characters or patterns on samples that could not be visualized by infrared inspection. Consequently, the EDD is considered to be applicable to other methods of detecting the indented writing impressions as a method for analyzing chemical property of color material components, fingerprint detection, visualization of static electricity traces without indentations and obliterated characters or patterns.
