US 12,326,693 B2
Piezoelectric balance spring, and method for manufacturing the balance spring
Alexandre Didier, Erlach (CH); François Gueissaz, Cormondrèche (CH); and Elias Laforge, Neuchâtel (CH)
Assigned to The Swatch Group Research and Development Ltd, Marin (CH)
Filed by The Swatch Group Research and Development Ltd, Marin (CH)
Filed on Sep. 7, 2022, as Appl. No. 17/939,511.
Claims priority of application No. 21213832 (EP), filed on Dec. 10, 2021.
Prior Publication US 2023/0185242 A1, Jun. 15, 2023
Int. Cl. G04B 17/06 (2006.01); G04B 17/22 (2006.01)
CPC G04B 17/063 (2013.01) [G04B 17/066 (2013.01); G04B 17/227 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A piezoelectric balance spring (3) comprising:
at least one piezoelectric layer (7, 7′, 17, 17′, 27, 27′) deposited on a top face (20) or bottom face of coils of the spring in a plane, and at least two pairs of electrodes (8a, 8b, 8c, 8d), wherein the electrodes of each pair are disposed on the same side as two opposing faces of at least one piezoelectric layer (7) or respectively two separate piezoelectric layers (7, 7′) so as to apply a reverse bias voltage on each pair of electrodes.