The Kurantbanken (also known as the københavnske Assignationsbanken, Vekselbanken or Laanebankbanken) was a Danish-Norwegian private limited company set up in Copenhagen in 1736, when it received its royal oktroj or charter. This charter gave it the right to issue banknotes as legal tender for the state (but not for other citizens) - these notes were to be fully convertible (for silver coin).
References
Kurantbanken Wikipedia(Text) CC BY-SA