Claims
- 1. A linear voice coil actuator comprisinga field assembly including a magnet located inside the field assembly and having an axis of magnetization; and a coil assembly positioned for movement along the axis of magnetization of the magnet including a coil; and a magnetic structure positioned coaxially with the axis of magnetization of the magnet so that the coil assembly is attracted to a soft magnetic pole piece attached to the magnet inside the field assembly when the coil is not energized.
- 2. The actuator of claim 1 wherein the magnet is a cylindrical magnet.
- 3. The actuator of claim 1 wherein the field assembly includesan axially magnetized magnet; a soft magnetic housing having a cavity, wherein the magnet has first and second ends along the axis of magnetization of the magnet, and so that a first end of the magnet is positioned on the housing in the cavity, and further wherein the soft magnetic pole piece is positioned on a second end of the magnet.
- 4. The actuator of claim 3 wherein the magnet and pole piece are positioned in the cavity of the housing to define a gap betw en sides of the cavity and the magnet and pole piece; and further wherein the coil is positioned in the gap.
- 5. The actuator of claim 4 wherein the magnet, pole piece, cavity, and coil have cylindrical shapes.
- 6. The actuator of claim 1, 2, 3, 4, or 5, wherein the magnetic structure is a plate constructed of magnetic material.
- 7. The actuator of claim 6 further including a stop positioned to limit the position of the magnetic structure relative to the magnet when the coil is not energized.
- 8. The actuator of claim 7 wherein the plate has a disc shape.
- 9. The actuator of claim 8 wherein the plate has a diameter and a thickness at least one of which is selected to control a latching force between the plate and the magnet.
- 10. The actuator of claim 8 wherein the plate has a diameter and a thickness at least one of which is selected to control a latching force when the coil is in a predetermined position and the coil is not energized.
- 11. The actuator of claim 10 wherein the predetermined position is defined by the stop.
- 12. A linear voice coil actuator comprisinga field assembly including an axially magnetized cylindrical magnet located inside the field assembly; a soft magnetic pole piece positioned on one end of the cylindrical magnet along the axis of magnetization of the cylindrical magnet; a soft magnetic housing having a circular cavity, wherein an end of the cylindrical magnet opposite the soft magnetic pole piece is positioned on the soft magnetic housing in the circular cavity to define a circular gap between the cylindrical magnet and the soft magnetic housing that is coaxial with the axis of magnetization of the cylindrical magnet; a coil assembly a least a portion of which is positioned in the circular gap for movement along the axis of magnetization of the magnet including a coil base having a circular cavity; a coil positioned in the circular cavity; and a magnetic plate having a diameter and a thickness and wherein the magnetic plate is attracted to a soft magnetic pole piece attached to the magnet inside the field assembly to latch the actuator with a latching force when the coil assembly is in a predetermined position in the circular gap and the coil is not energized; and a stop positioned to define the predetermined position of the coil assembly.
- 13. The linear actuator of claim 12 wherein the thickness of the magnetic plate is selected to set the latching force of the actuator.
- 14. The linear actuator of claim 12 wherein the diameter of the magnetic plate is selected to set the latching force of the actuator.
RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119(e) from provisional application No. 60/322,410, filed Sep. 14, 2001.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
4363980 |
Petersen |
Dec 1982 |
A |
6269168 |
Tagami |
Jul 2001 |
B1 |
Foreign Referenced Citations (3)
Number |
Date |
Country |
1 149 094 |
Nov 1956 |
DE |
61-104375 |
May 1986 |
JP |
11-299211 |
Oct 1999 |
JP |
Non-Patent Literature Citations (1)
Entry |
International Search Report dated Jul. 11, 2003. |
Provisional Applications (1)
|
Number |
Date |
Country |
|
60/322410 |
Sep 2001 |
US |