Ricoh Co. said Tuesday it has developed a printer-photocopier capable of automatically blocking the unauthorized duplication of classified documents.

When a machine user prints out classified documents from the personal computer on which they were drawn up, it imprints masked dotted patterns that are dimly visible on the surface of the printouts, the company said.

If another person tries to make a photocopy of these documents with masked patterns on the new copier, it will recognize the patterns and discharge blank gray paper instead of duplicating the documents, the company said.

In this way the new machine "aborts efforts to duplicate confidential documents," a Ricoh official said.

The machine could be instrumental in preventing leaks of confidential data from companies, as classified information is more often leaked through unauthorized duplication of hard copy than through computers.

The machine goes on the market in February.

Even if a person makes a photocopy of documents bearing such patterns by using non-Ricoh copiers, the printouts will be garbled because hitherto-masked characters reading "Duplication Unauthorized" will suddenly appear on the surface of copies, Ricoh said.

The company developed the machine as "companies and government agencies are keen to ensure the security of their information," a Ricoh spokesman said.