PLANAR ACOUSTIC CONVERTER Russian patent published in 2002 - IPC

FIELD: radio engineering. SUBSTANCE: yoke 20 carries permanent magnets m18, m28 and m38 each having planar rectangular shape. Their pole surfaces face upwards with alternation of opposite polarities. Mobile membrane 26 which is parallel to pole surfaces of permanent magnets is positioned on upper surface of yoke 20. Pairs of coils L18, L28 and L38 coming in the form of spirals and so mounted that they are located opposite corresponding permanent magnets m18, m28 and m38 are put on upper and rear surfaces of mobile membrane. Each pair of coils L18, L28 and L38 is wound along spiral practically following outline of external edge of pole surface of each permanent magnet m18, m28 and m38. Internal boundary of each coil lies in zone outside of limits of section corresponding to external edge of pole surface so that external peripheral sections of coils do not superimpose one on another. Due to this pairs of coils L18, L28 and L38 couple only those magnetic fluxes which are oriented along surface of mobile membrane. EFFECT: reduced level of noise components of converter, raised quality of sound, simplified technology of manufacture. 11 cl, 22 dwg