METHODS AND APPARATUS FOR REDUCED DISTORTION BALANCED ARMATURE DEVICES
First Claim
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1. A balanced armature apparatus, comprising:
- a first permanent magnet;
a second permanent magnet;
an armature, having an end portion located between the first permanent magnet and the second permanent magnet; and
a coil, the coil being magnetically coupled to the armature, the coil being energizable by a drive signal so as to induce a flux level within the armature and a deflection of the end portion of the armature,a displacement relationship relating the displacement to a drive signal level,the armature being configured to have a reluctance that increases with the drive signal level so as to improve linearity of the displacement relationship, for flux levels less than those required to initiate saturation of the entire armature.
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Abstract
An example apparatus comprises a drive coil energizable by a drive signal, at least one permanent magnet and at least one magnetic return path element for flux induced by the drive signal, the magnetic return path element, such as a balanced armature, being configured to provide a variable reluctance, so as to reduce nonlinearities in a displacement versus drive signal relationship. Modifying the reluctance versus flux properties of the magnetic return path of a transducer, e.g. the armature of a balanced armature device, allows compensation for nonlinearity arising in another part of the apparatus.
53 Citations
23 Claims
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1. A balanced armature apparatus, comprising:
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a first permanent magnet; a second permanent magnet; an armature, having an end portion located between the first permanent magnet and the second permanent magnet; and a coil, the coil being magnetically coupled to the armature, the coil being energizable by a drive signal so as to induce a flux level within the armature and a deflection of the end portion of the armature, a displacement relationship relating the displacement to a drive signal level, the armature being configured to have a reluctance that increases with the drive signal level so as to improve linearity of the displacement relationship, for flux levels less than those required to initiate saturation of the entire armature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus, the apparatus being an armature for a balanced armature device,
the armature having an armature saturation flux at which the armature is completely saturated, the armature including a multi-layer portion including: -
a first layer including a partial saturation region, the partial saturation region being saturated by an armature flux level less than the armature saturation flux; and a second layer operational as a flux shunt around the partial saturation region when the partial saturation region is saturated. - View Dependent Claims (13, 14, 15, 16, 17)
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18. An apparatus, the apparatus being a magnetic apparatus comprising:
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an armature; a coil, the coil being energizable by a drive signal so as to induce a flux within the armature; and at least one permanent magnet; the armature having an equilibrium position with no drive signal applied, a portion of the armature being displaceable relative to the equilibrium position by the drive signal so as to have a displacement correlated with a drive signal level up to a saturation flux of the armature, the armature being configured to have an armature reluctance that increases with flux level for flux levels substantially below the saturation flux, so as to obtain a generally linear relationship between the displacement and the drive signal level. - View Dependent Claims (19, 20, 21, 22, 23)
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Specification