| US 7,501,834 B2 | ||
| Voice coil actuator with embedded capacitive sensor for motion, position and/or acceleration detection | ||
| Asad M. Madni, Los Angeles, Calif. (US); Jim B. Vuong, Northridge, Calif. (US); and Robert K. Hansen, Burbank, Calif. (US) | ||
| Assigned to Custom Sensors & Technologies, Inc., Moorpark, Calif. (US) | ||
| Filed on Jun. 21, 2005, as Appl. No. 11/159,572. | ||
| Prior Publication US 2007/0003099 A1, Jan. 04, 2007 | ||
| Int. Cl. G01R 27/26 (2006.01); H04R 9/06 (2006.01) | ||
| U.S. Cl. 324—658 [381/400] | 20 Claims |
| 1. A voice coil actuator having a capacitive sensor, comprising:
a magnetic housing containing at least one magnet, the magnetic housing having a wall that defines a first cavity;
a magnetic core coupled to the magnetic housing and extending from an interior surface of the magnetic housing in a direction
of a center axis of the wall of the magnetic housing; and
a coil assembly having a wall defining a second cavity that at least partly envelops the magnetic core, disposed at least
partly inside the first cavity, and adapted to move linearly with respect to the magnetic housing, wherein the coil assembly
has formed thereon at least two electrically conducive areas;
wherein the coil assembly forms the capacitive sensor with the magnetic core, the capacitive sensor adapted to measure at
least one of position, velocity and acceleration of the coil assembly with respect to the magnetic housing; and
wherein the magnetic core comprises a wall defining a third cavity, and the coil assembly has formed thereon an insulated
rod that extends from an interior surface of the coil assembly into the third cavity, wherein the insulated rod has disposed
thereon a pair of electrically conductive areas that form a capacitor with each other and form respective capacitors with
the wall of the magnetic core, thereby forming the capacitive sensor.
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