Plate archives of astronomical observatories contain huge volumes of observations only partally processed as usual. These observations include the unique information on astronomical objects and events which can not be obtained or restored with the help of other modern facilities, space missions included. We propose a concept of a hardware-software complex which will realise an effective extraction of this information. With the help of a commercial flat-bed scanner and base package of software, it is supposed to create the data base and archive of electronic clones of plates by the way of digitization with a sampling up to 20 microns. A fast monitoring of an archive of electronic clones is performed with the help of problem-oriented software. A modular structure of the system basic software and standard format of the plate image files allow a future development of problem oriented software for special astronomical researches including cooperative projects with observational programs, transporting of plate images through the Internet as well as open the capability for creation a distributed network of digital archives.