US 12,225,366 B2
Acoustic transducer with balanced properties
Petri Soronen, Oulu (FI); Vesa Kajanus, Oulu (FI); Petteri Luukkanen, Oulu (FI); Mikko Mäkelä, Oulu (FI); and Eero Yli-Rantala, Oulu (FI)
Assigned to PS Audio Design Oy, Oulu (FI)
Appl. No. 17/907,097
Filed by PS Audio Design Oy, Oulu (FI)
PCT Filed Dec. 29, 2020, PCT No. PCT/FI2020/050872
§ 371(c)(1), (2) Date Sep. 22, 2022,
PCT Pub. No. WO2021/191492, PCT Pub. Date Sep. 30, 2021.
Claims priority of application No. 20205298 (FI), filed on Mar. 25, 2020.
Prior Publication US 2024/0223959 A1, Jul. 4, 2024
Int. Cl. H04R 9/06 (2006.01); H04R 1/02 (2006.01); H04R 9/02 (2006.01); H04R 9/04 (2006.01)
CPC H04R 9/06 (2013.01) [H04R 1/028 (2013.01); H04R 9/025 (2013.01); H04R 9/045 (2013.01); H04R 2400/11 (2013.01); H04R 2499/15 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An acoustic transducer for converting electric signals into mechanical vibrations on acoustic frequencies, the acoustic transducer comprising:
an upper part and a lower part;
a first permanent magnet located in the upper part and a second permanent magnet located in the lower part, with same named magnetic poles of the first and second permanent magnets facing each other in the direction of an axis line;
an upper cover in the upper part and a lower cover in the lower part, said upper and lower covers comprising magnetic material and together defining an enclosure around the first and second permanent magnets; and
at least one coil located in said enclosure and configured to create, under influence of an electric current flowing through said coil, dynamic magnetic forces in the direction of said axis line;
wherein a separating gap between edges of said upper cover and lower cover is directed essentially in the direction of said axis line, allowing a relative movement of the edges of said lower cover and said upper cover in the direction of said axis line between different positions, said positions differing in the extent to which said edges of said upper cover and lower cover coincide in the direction perpendicular to said axis line;
wherein said upper cover has a U-formed cross section, with said first permanent magnet located inside the loop of the U-formed cross section;
wherein said lower cover has a plate-formed cross section, with an outer edge of the plate defining said edge of the lower cover; and
wherein said second permanent magnet is on that side of the plate that faces the inside of the U-formed cross section of the upper cover.