Research On The Characteristics Of The Common Laser Printing Documents

Laser printers are the most commonly used mechanism document makingtools now, they upgrading fast but lacking of system research on theirdocuments, can not adapt to the examining of laser printing documents.This article is the early research on <Key techniques of nondest-ructive examination of mechanism document>, focus on the the currentcommon laser printers and their printing documents. Research processedthrough the three stages: First of all, to know the laser printer andanalysed their market survey. Secondly, combined with laser printer testsamples, in accordance with the need of actual examine cases, designedour experimental samples. Finally, collected common laser printer’sprinting documents and then did the analysis and research.Experiment has collected hundreds of experimental samples, involving77kinds of different models of laser printer, most of them are black andwhite laser printers with600x600dpi or1200x1200dpi, almost reflectsthe current commonly used laser printers. With the combination of videospectral comparator and microscope, it carries out the summary on thetracking codes and toner characteristics. In the examination of videospectral comparator, printing documents of color laser printers may appear tracking codes, which can be used for the identification ofdifferent brands. But now we can not completely explain all the meaningof the tracking codes. And most of the tracking codes will not change overtime, therefore it can not be used for the identification of formationtime of a laser printing document. Microscopic examination has found thatdue to the high quality of laser printing, there are not obviousdifferences in toner characteristics within the same brand or evendifferent brand of printing documents.The results of this research to a certain extent can improve theidentification efficiency， and probative force of laser printingdocuments, hence to provide technical reference for all types of laserprinting documentary evidence for investigation, trial and public affairshandling.