German inventor, of a direction-finder for pilots (1927), and of the Hellschreiber, a precursor to the fax machine (1929). In 1929 he started his company in Berlin, and went on to make radio direction finders and radio compasses. During the Second World War he made encoders and acoustic mine exploders; by its end his premises had been destroyed by Allied bombing.

In 1947 he started a new company, based in Kiel and called Dr. Ing. Rudolf Hell GmbH. The business started off repairing Hellschreiber machines, but went on to produce his invention of an electronically controlled printing block engraver, the Klischograph.

In 1964 he invented the Digiset, the first digital typesetter. Hermann Zapf and Gerard Unger designed original fonts specially for these high quality, high production machines. In the late 1970s the company became a subsidiary of Siemens, but Rudolf Hell continued at the helm until the 1990 merger with Linotype AG.