Integrated micro actuator and LVDT for high precision position measurements
View Patent ↗A single housing with a non-ferromagnetic piezo-driven flexure has primary and secondary coil forms of different diameters, one coaxially inside the other, integrated in the flexure. The cylinders defining the planes of the primary and secondaries do not spatially overlap. The secondary coil forms may be wound in opposite directions and wired to provide a transformer device. Movement of the primary relative to the secondaries in the direction of the central axis of the coils can be differentially detected with high precision.
1. A method, comprising:
placing a sample to be tested on a top surface of one part of a housing;
moving said top surface with the sample to be tested relative to another part of the housing, where said one part of said housing is movable relative to the another part of the housing, and where said moving is in a z-axis direction substantially perpendicular to said top surface and where said moving in the z-axis direction uses a flexure to change a vertical position of the top surface; and
differentially detecting said moving of said top surface with the sample to be tested relative to the another part of the housing and producing an output signal indicative thereof,
wherein said top surface includes a screwable connection part which allows said flexure to be preloaded.
2. A detector, comprising:
a housing, having a top surface that holds a sample to be tested on one part of the top surface, and having and side surfaces that are perpendicular to said top surface;
said top surface controlled to move, by actuating a moving part to move said top surface with the sample held on the top surface,
said moving part moving one part of the housing relative to another part of the housing when actuated, where said one part moves in a z-axis direction substantially perpendicular to said top surface; and
a differential detector, differentially detecting movement of said one part with the sample to be tested on said one part of the housing relative to the housing and producing an output signal indicative thereof, wherein said one part of said housing includes an energized primary coil wound on a primary coil surface that is substantially perpendicular to said top surface, and said another part of said housing includes first and second parts of a secondary coil wound on a secondary coil surface that is substantially perpendicular to said top surface.
3. The detector as in claim 2 , wherein said secondary coil surface includes said side surfaces of said housing.
4. The detector as in claim 2 , wherein said sample is moved on said top surface with the sample to be tested in x and y directions that are substantially perpendicular to each other and parallel to said top surface, and where a separation is maintained between a probe and said sample to allow room for movement in said z-axis direction, wherein said one part of said housing includes an energized primary coil wound on a primary coil surface that is substantially perpendicular to said top surface, and said another part of said housing includes first and second parts of a secondary coil wound on a secondary coil surface that is substantially perpendicular to said top surface, and separated from said primary coil surface in said x and y directions.
5. The detector as in claim 4 , wherein said secondary coil surface includes said side surfaces of said housing.
6. The detector as in claim 4 , further comprising electrically connecting said primary and secondary coils through a conduit in said housing.
7. The detector as in claim 6 , wherein said differential detector has connections to first and second parts of said secondary coil.
8. The detector as in claim 2 , further comprising electrically connecting said primary and secondary coils through a conduit in said housing.
9. The detector as in claim 2 , wherein said differential detector connects to first and second portions of said secondary coil.
10. The detector as in claim 2 , wherein said moving part is a piezo-driven flexure, where said movement is in a z-axis direction substantially perpendicular to said top surface and moves said top surface with the sample to be tested relative to another part of the housing.
11. The detector as in claim 2 , wherein said housing includes a flexure that has a plurality of surfaces which flex relative to one another based on movement of the sample, and which, when flexing, cause movement between said primary coil and said secondary coil, said movement being constrained to the z-axis direction with very little motion in the direction of x and y axes.
12. A device as in claim 11 , wherein said top surface includes a screwable connection part which allows said flexure to be preloaded.
13. A device as in claim 12 , wherein said top surface is a spring-loaded surface with the sample to be tested, where said top surface is moved relative to another part of the housing by a piezo-driven flexure, where said movement is in a z-axis direction substantially perpendicular to said top surface.
14. A transformer device, comprising:
a housing, having a first surface holding a sample, and said housing having structure allowing said sample to move relative to said housing along a first axis, and said housing having second and third coaxially located surfaces, said second surface allowing winding a primary coil thereon, and said third surface allowing winding of first and second parts of a secondary coil thereon, and said second and third surfaces being movable relative to each other in a substantially parallel direction to one another along a second axis, where movement along the second axis being a function of the movement of said sample along the first axis based on movement of said sample; and
wherein said first surface is a spring-loaded surface, and
wherein said spring loaded surface is moved relative to another part of the housing by a piezo-driven flexure, where said movement is in a z-axis direction substantially perpendicular to said spring loaded surface.