Speaker apparatus
AssigneeSony Corporation
InventorYoshio Ohashi
Life of this patent
Estimating the term…
Abstract
In an electromagnetic induction type speaker apparatus, individual constants are set in such a manner that the following formula is satisfied N×(R1×R2)1/2/(2π×L1×(1−k2)1/2>2000 where R1 is the DC resistance of a primary coil; L1 is the inductance of the primary coil; N is the number of turns of the primary coil; R2 is the DC resistance of the secondary coil; L2 is the inductance of the secondary coil; and k is the coupling coefficient of the primary coil and the secondary coil. In addition, the constants L1 and l2 are selected in such a manner that the ratio of the inductance L1 and the inductance L2 becomes equal to the ratio of the DC resistance R1 and the DC resistance R2.
Claims2
A speaker apparatus, comprising:
- a primary coil arranged on a fixed pole piece and disposed in a vicinity of a gap of a magnetic circuit and to which a current corresponding to an input audio signal is supplied;
- a one-turn cylindrical ring forming a secondary coil, arranged on a movable bobbin and disposed in the gap for having induced therein a current corresponding to a current that flows in said primary coil, and being movable relative to said primary coil;
- and
- a vibrating plate attached said bobbin and vibrated by said secondary coil with an interaction of the current induced by said secondary coil and a magnetic flux in the gap,
- wherein the following relation is satisfied
- L1/L2=R1/R2
- Wherein R1 is a DC resistance of said primary coil;
- L1 is an inductance of said primary coil;
- R2 is a DC resistance of said secondary coil;
- and L2 is an inductance of said secondary coil.
Dependencies are inferred from the claim text.