Fringe field capacitive sensor for measuring the size of an opening

Claim 1

An apparatus for measuring the size of an opening in a conductive body along a measurement direction, the apparatus comprising: a probe having a probe axis and adapted to be inserted in the opening; two plate elements mounted by the probe such that the plate elements are parallel to one another and normal to the probe axis, the plate elements being spaced apart from one another in a direction normal to the probe axis, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending across the width of the plate element; positioning means for positioning the probe such that the probe axis is approximately normal to the measurement direction and such that the plate elements are within the opening and positioned adjacent to and normal to respective body surfaces thereof such that each edge is positioned in a generally parallel relationship to its respective body surface, the body surfaces being spaced apart from one another along the measurement direction, the positioning means including means for causing relative movement between the probe and the body such that the probe moves within the opening along a scanning direction parallel to the probe axis; and measurement means for measuring the fringe field capacitance between each plate element and the body at a plurality of probe positions along the scanning direction, wherein the measurement means alternately selects one plate element and then the other for said measurement selectively energizing only one plate element at a time for each measurement to avoid interference between the measurements, and thereby determining the distance between each plate element and its respective body surface as a function of probe position along the scanning direction at the time that the plate element is selected.

Claim 2

An apparatus for measuring the size of an opening in a conductive body along a measurement direction, the apparatus comprising: a probe having a probe axis and adapted to be inserted in the opening; two plate elements mounted by the probe such that the plate elements are parallel to one another and normal to the probe axis, the plate elements being spaced apart from one another in a direction normal to the probe axis, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending across the width of the plate element; positioning means for positioning the probe such that the probe axis is approximately normal to the measurement direction and such that the plate elements are within the opening and positioned adjacent to and normal to respective body surfaces thereof such that each edge is positioned in a generally parallel relationship to its respective body surface, the body surfaces being spaced apart from one another along the measurement direction, the positioning means including means for causing relative movement between the probe and the body such that the probe moves within the opening along a scanning direction parallel to the probe axis; and measurement means for measuring the fringe field capacitance between each plate element and the body at a plurality of probe positions along the scanning direction, wherein the measurement means alternately selects one plate element and then the other for said measurement selectively energizing only one plate element at a time for each measurement to avoid interference between the measurements, and thereby determining the distance between each plate element and its respective body surface as a function of probe position along the scanning direction at the time that the plate element is selected.

Claim 8

A method for measuring the size of an opening in a conductive body along a measurement direction, comprising: providing a probe having a probe axis and adapted to be inserted in the opening, the probe including two plate elements parallel to one another and normal to the probe axis, and spaced apart from one another in a direction normal to the probe axis, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending along the width of the plate element; positioning the probe such that the probe axis is approximately normal to the measurement direction and such that the plate elements are within the opening and positioned adjacent to and normal to respective body surfaces thereof, such that the edge is positioned in a generally parallel relationship to its respective body surface, the body surfaces being spaced apart from one another along the measurement direction; causing relative movement between the probe and body such that the probe moves within the opening along a scanning direction parallel to the probe axis; and measuring the fringe field capacitance between each plate element and the body at a plurality of probe positions along the scanning direction, alternating between the plate elements while making said measurements, and selectively energizing only one plate element at a time for each measurement to avoid interference between the measurements, and thereby determining the distance between each plate element and its respective body surface along the measurement direction as a function of probe position along the scanning direction at the time of the measurement for the plate element.

Claim 9

A method for measuring the size of an opening in a conductive body along a measurement direction, comprising: providing a probe having a probe axis and adapted to be inserted in the opening, the probe including two plate elements parallel to one another and normal to the probe axis, and spaced apart from one another in a direction normal to the probe axis, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending along the width of the plate element; positioning the probe such that the probe axis is approximately normal to the measurement direction and such that the plate elements are within the opening and positioned adjacent to and normal to respective body surfaces thereof, such that the edge is positioned in a generally parallel relationship to its respective body surface, the body surfaces being spaced apart from one another along the measurement direction; causing relative movement between the probe and body such that the probe moves within the opening along a scanning direction parallel to the probe axis; and measuring the fringe field capacitance between each plate element and the body at a plurality of probe positions along the scanning direction, alternating between the plate elements while making said measurements, and selectively energizing only one plate element at a time for each measurement to avoid interference between the measurements, and thereby determining the distance between each plate element and its respective body surface along the measurement direction as a function of probe position along the scanning direction at the time of the measurement for the plate element.

Claim 15

An apparatus for measuring the shape of a surface of a body along a measurement direction, comprising: a probe; a plurality of conductive plate elements mounted by the probe, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending along the width of the plate element; positioning means for positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that each edge is positioned in a generally parallel relationship to the body surface, and such that the plate elements are spaced from one another along the measurement direction; and measurement means for measuring the fringe field capacitance between each plate element and the body in sequence over time by energizing only one plate element at a time for each measurement to avoid interference between the measurements, and thereby measuring the distance between each plate element and the body when said fringe field capacitance measurement for the plate element is made.

Claim 16

An apparatus for measuring the shape of a surface of a body along a measurement direction, comprising: a probe; a plurality of conductive plate elements mounted by the probe, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending along the width of the plate element; positioning means for positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that each edge is positioned in a generally parallel relationship to the body surface, and such that the plate elements are spaced from one another along the measurement direction; and measurement means for measuring the fringe field capacitance between each plate element and the body in sequence over time by energizing only one plate element at a time for each measurement to avoid interference between the measurements, and thereby measuring the distance between each plate element and the body when said fringe field capacitance measurement for the plate element is made.

Claim 21

A method for measuring the shape of a surface of a body along a measurement direction, the method comprising: providing a probe having a plurality of conductive plate elements mounted by the probe, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending along the width of the plate element; positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that each edge is positioned in a generally parallel relationship to the body surface and such that the plate elements are spaced from one another along the measurement direction; and measuring the fringe field capacitance between each plate element and the body in sequence over time, selectively energizing only one plate at a time for each measurement to avoid interference between the measurements, and thereby measuring the distance between each plate element and the body when said fringe field capacitance measurement is made.

Claim 22

A method for measuring the shape of a surface of a body along a measurement direction, the method comprising: providing a probe having a plurality of conductive plate elements mounted by the probe, the thickness of each plate element being substantially less than the height and width of the plate element, each plate element including an edge extending along the width of the plate element; positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that each edge is positioned in a generally parallel relationship to the body surface and such that the plate elements are spaced from one another along the measurement direction; and measuring the fringe field capacitance between each plate element and the body in sequence over time, selectively energizing only one plate at a time for each measurement to avoid interference between the measurements, and thereby measuring the distance between each plate element and the body when said fringe field capacitance measurement is made.

Claim 25

An apparatus for measuring the size of an opening in a conductive body along a measurement direction, comprising: a probe having a probe axis and adapted to be inserted in an opening; a plurality of plate elements mounted by the probe such that the plate elements are parallel to one another, normal to and spaced apart around the probe axis; the thickness of each plate element being substantially less than the height, H, and width, W, of the plate element measured across an edge thereof; positioning means for positioning the probe such that the plate elements are within the opening, adjacent to and generally normal to an inner surface of the opening, the edge of each plate element being positioned in a generally parallel relationship to said surface, the positioning means including means for causing relative movement between the probe and the body such that the probe moves within the opening along a scanning direction generally parallel to the probe axis; and measurement means for measuring the fringe field capacitance, C, between each plate element and the body at a plurality of probe positions along the scanning direction, substantially as defined by ##EQU10## where: e is the dielectric constant of the probe; h is the distance between the edge of a plate element and the inner surface of the opening; and said measuring means being thus further operative to determine the size of the opening as a function of h, at the plurality of probe positions by appropriately combining the measurements made with the plate elements, for each probe position.

Claim 26

An apparatus for measuring the size of an opening in a conductive body along a measurement direction, comprising: a probe having a probe axis and adapted to be inserted in an opening; a plurality of plate elements mounted by the probe such that the plate elements are parallel to one another, normal to and spaced apart around the probe axis; the thickness of each plate element being substantially less than the height, H, and width, W, of the plate element measured across an edge thereof; positioning means for positioning the probe such that the plate elements are within the opening, adjacent to and generally normal to an inner surface of the opening, the edge of each plate element being positioned in a generally parallel relationship to said surface, the positioning means including means for causing relative movement between the probe and the body such that the probe moves within the opening along a scanning direction generally parallel to the probe axis; and measurement means for measuring the fringe field capacitance, C, between each plate element and the body at a plurality of probe positions along the scanning direction, substantially as defined by ##EQU10## where: e is the dielectric constant of the probe; h is the distance between the edge of a plate element and the inner surface of the opening; and said measuring means being thus further operative to determine the size of the opening as a function of h, at the plurality of probe positions by appropriately combining the measurements made with the plate elements, for each probe position.

Claim 27

A method for measuring the size of an opening in a conductive body along a measurement direction, comprising; providing a probe having a probe axis and adapted to be inserted in the opening, the probe including a plurality of spaced apart plate elements that are substantially parallel to one another and normal to the probe axis, the thickness of each plate element being substantially less than the height, H, and width, W, of the plate element measured across an edge thereof; positioning the probe such that the probe axis is approximately normal to the measurement direction and such that the plate elements are within the opening, adjacent to and normal to an inner surface thereof, with the edge of each plate element being positioned in a generally parallel relationship to its respective body surface; causing relative movement between the probe and body such that the probe moves within the opening along a scanning direction parallel to the probe axis; measuring the fringe field capacitance, C, between each plate element and the inner surface of the opening at a plurality of probe positions along the scanning direction, substantially as defined by ##EQU11## wherein: e is the dielectric constant of the probe; h is the edge of a plate element and the inner surface of the opening; and determining the size of the opening as a function of h, by appropriately combining the measurements made with the plate elements for each of the plurality of probe positions.

Claim 28

A method for measuring the size of an opening in a conductive body along a measurement direction, comprising; providing a probe having a probe axis and adapted to be inserted in the opening, the probe including a plurality of spaced apart plate elements that are substantially parallel to one another and normal to the probe axis, the thickness of each plate element being substantially less than the height, H, and width, W, of the plate element measured across an edge thereof; positioning the probe such that the probe axis is approximately normal to the measurement direction and such that the plate elements are within the opening, adjacent to and normal to an inner surface thereof, with the edge of each plate element being positioned in a generally parallel relationship to its respective body surface; causing relative movement between the probe and body such that the probe moves within the opening along a scanning direction parallel to the probe axis; measuring the fringe field capacitance, C, between each plate element and the inner surface of the opening at a plurality of probe positions along the scanning direction, substantially as defined by ##EQU11## wherein: e is the dielectric constant of the probe; h is the edge of a plate element and the inner surface of the opening; and determining the size of the opening as a function of h, by appropriately combining the measurements made with the plate elements for each of the plurality of probe positions.

Claim 29

An apparatus for measuring the shape of a body along a measurement direction, comprising: a probe; a plurality of conductive plate elements mounted by the probe, the thickness of each plate being substantially less than the height, H, and width, W, of the plate element, measured along an edge thereof; positioning means for positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that teach edge is positioned in a generally parallel relationship to the body surface, and such that the plate elements are spaced from one another along the measurement direction; and measurement means for measuring the fringe field capacitance, C, between each plate element and the body at a plurality of measurement positions, C being substantially defined by ##EQU12## where: e is the dielectric constant of the probe; h is the spacing between the edge of a plate element and the body; and said measurement means including means to determine the shape of the surface as a function of successive values of h for each plate element in respect to variations in the value of h for the plate elements along the measurement direction at each measurement position.

Claim 30

An apparatus for measuring the shape of a body along a measurement direction, comprising: a probe; a plurality of conductive plate elements mounted by the probe, the thickness of each plate being substantially less than the height, H, and width, W, of the plate element, measured along an edge thereof; positioning means for positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that teach edge is positioned in a generally parallel relationship to the body surface, and such that the plate elements are spaced from one another along the measurement direction; and measurement means for measuring the fringe field capacitance, C, between each plate element and the body at a plurality of measurement positions, C being substantially defined by ##EQU12## where: e is the dielectric constant of the probe; h is the spacing between the edge of a plate element and the body; and said measurement means including means to determine the shape of the surface as a function of successive values of h for each plate element in respect to variations in the value of h for the plate elements along the measurement direction at each measurement position.

Claim 31

A method for measuring the shape of a surface of a body along a measurement direction, comprising the steps of: providing a probe having a plurality of conductive plate elements mounted by the probe, the thickness of each plate element being substantially less than the height, H, and width, W, of the plate element, measured along an edge thereof; positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that each edge is positioned in a generally parallel relationship to the body surface and such that the plate elements are spaced from one another along the measurement direction; at a plurality of measurement positions, measuring the fringe field capacitance, C, between each plate element and the body, substantially as defined by ##EQU13## where: e is the dielectric constant of the probe; h is the spacing between the edge of a probe element and the body; and determining the shape of the surface of the body as a function of successive values of h for each plate element in respect to variations in the value of h for the plate elements along the measurement direction at each measurement position.

Claim 32

A method for measuring the shape of a surface of a body along a measurement direction, comprising the steps of: providing a probe having a plurality of conductive plate elements mounted by the probe, the thickness of each plate element being substantially less than the height, H, and width, W, of the plate element, measured along an edge thereof; positioning the probe adjacent the surface such that the plate elements are normal to the surface and such that each edge is positioned in a generally parallel relationship to the body surface and such that the plate elements are spaced from one another along the measurement direction; at a plurality of measurement positions, measuring the fringe field capacitance, C, between each plate element and the body, substantially as defined by ##EQU13## where: e is the dielectric constant of the probe; h is the spacing between the edge of a probe element and the body; and determining the shape of the surface of the body as a function of successive values of h for each plate element in respect to variations in the value of h for the plate elements along the measurement direction at each measurement position.