US 11,729,555 B2
Adjustable magnetic spring for actuator
Franz Heidinger, Unterwaltersdorf (AT); Manuel Mefleh, Vienna (AT); Gustav Otto, Vienna (AT); Friedrich Reining, Vienna (AT); and Michael Schoffmann, Baden (AT)
Assigned to Sound Solutions International Co., Ltd., Beijing (CN)
Filed by Sound Solutions International Co., Ltd., Beijing (CN)
Filed on Jan. 5, 2022, as Appl. No. 17/569,391.
Claims priority of application No. 50005/2021 (AT), filed on Jan. 12, 2021.
Prior Publication US 2022/0232326 A1, Jul. 21, 2022
Int. Cl. H04R 9/02 (2006.01); H04R 11/02 (2006.01); H02K 33/16 (2006.01)
CPC H04R 9/025 (2013.01) [H02K 33/16 (2013.01); H04R 11/02 (2013.01)] 24 Claims
OG exemplary drawing
 
1. An electrodynamic actuator (1a, 1b), which is designed to be connected to a backside of a plate like structure (2) opposite to a sound emanating surface (S) of the plate like structure (2), and which comprises:
a coil arrangement (3a, 3b) with at least one voice coil (4a, 4b), which has an electrical conductor in the shape of loops running around a coil axis (C) in a loop section;
a magnet system (5), comprising a static magnetic circuit part (6a . . . 6F), which is arranged in fixed relation to the coil arrangement (3a, 3b), and a movable magnetic circuit part (7, 7a . . . 7f), wherein the magnet system (5) is designed to generate a magnetic field (B1, B2) transverse to the conductor in the loop section; and
a spring arrangement (12) coupling the static magnetic circuit part (6a . . . 6F) to the movable magnetic circuit part (7, 7a . . . 7f) and allowing a relative movement between the static magnetic circuit part (6a . . . 6F) and said movable magnetic circuit part (7, 7a . . . 7f) in an excursion direction (z) parallel to the coil axis (C),
wherein both the spring arrangement (12) and the magnet system (5) provide a total restoring force (FT) directed towards an idle position (P0) of the movable magnetic circuit part (7, 7a . . . 7f), which idle position (P0) is defined as the position of the movable magnetic circuit part (7, 7a . . . 7f) when no current (I) flows through the at least one voice coil (4a, 4b),
wherein a ratio between a differential total restoring force (ΔFT) and a differential excursion (Δz) of the movable magnetic circuit part (7, 7a . . . 7f) is defined as a total restoring force gradient (ΔFT/Δz), and
wherein a part of the total restoring force gradient (ΔFT/Δz) caused by the magnet system (5) is at least 10% of the total restoring force gradient (ΔFT/Δz) in said idle position (P0) of the movable magnetic circuit part (7, 7a . . . 7f).