Cyrill Demian received a patent for an early accordion in 1829 in Vienna.
Demian’s patent described an instrument with bellows and buttons that produced chords, making it different from later piano-key accordions. His sons, Karl and Guido, were named as collaborators in the patent. The design helped establish the accordion’s characteristic combination of bellows, reeds, and manual controls.
The accordion’s history includes several related free-reed instruments, so no single invention instantly produced the modern form. Later makers changed the keyboard, button layouts, reed organization, and bass systems.
Accordions produce sound when air from the bellows passes over free reeds. Different button or keyboard systems developed in different regions, including the chromatic button accordion, diatonic button accordion, and piano accordion.