US 7,216,054 B1 · Electromagnetic method and apparatus for the measurement of linear position

Abstract

A method and apparatus are disclosed for monitoring a linear position, such as the distance between a sensing element and a movable object, and/or related parameters, such as displacement, direction, speed, velocity, and/or acceleration. The method utilizes a sensing element and an electrically conductive portion of the movable object, or a conductive target coupled to the movable object. The apparatus includes at least one sensing element formed by a section of a coupled slow-wave structure. The sensing element is connected to an RF or microwave generator, and an electronic circuit that converts at least one electromagnetic parameter of the section of the coupled slow-wave structure into a position reading. Electric and magnetic fields excited in the sensing element are split so that most of the electric energy is concentrated inside of the sensing element, while most of the magnetic energy is concentrated outside of the sensing element. The distance that defines the linear position is measured as a resonant frequency, impedance, phase shift or other electromagnetic parameter.

Claims11

Dependent claims

A method for monitoring a position of an object, or related parameters, including a measurement of the position of the object as a distance between the object and a sensing element, motion of the object along the distance defining a motion axis, the method comprising:

placing at least one electromagnetic sensing element in proximity to the monitored object;
exciting an alternating electromagnetic field in the sensing element at a frequency and in a form at which the electromagnetic field extends to the object;
measuring a variation of at least one electromagnetic parameter of the sensing element, the variation caused by a variation in the position of the object;
converting results of the measurements into a representation of the position of the object along the motion axis,
wherein
at least one electrically conductive surface is formed on, or coupled to, the monitored object, the surface facing the sensing element, the alternating electromagnetic field exited as an opposite-phase slowed-wave in a coupled slow wave structure, the electromagnetic field having a spatial distribution, the distribution depending on the position of the conductive surface;
and
providing an indication of the position of the object.

5 more elements

An apparatus for monitoring a position of an object, including a measurement of the position of the object as a distance between the object and a sensing element, motion of the object along the distance defining a motion axis, the apparatus comprising:

at least one electromagnetic sensing element;
at least one target having an electrically conductive surface, the target located proximate the monitored object;
and
a measuring circuit connected to the sensing element, the circuit including:
at least one radio frequency or microwave generator;
and
a converter convening electromagnetic parameters of the sensing element into an electrical representation of linear position,
wherein:
the sensing element including at least one section of a coupled slow-wave structure, the generator exciting a slowed-wave into the sensing element, the slowed wave propagating in a direction, the section of coupled slow-wave structure having at least two impedance conductors configured as patterns, the patterns fashioned as at least one row of conductive members arranged in series in the direction of the slowed wave propagation and connected to one another with a pitch, h;
and
the pattern configurations of the impedance conductors being mirror images of one another flipped by approximately 180 degrees with respect to a surface of symmetry of the patterns, the patterns being set to distribute in a given ratio the components of electric and magnetic fields at the conductive surface of the target.

8 more elements

Dependencies are inferred from the claim text.

Electromagnetic method and apparatus for the measurement of linear position

Life of this patent

Electromagnetic method and apparatus for the measurement of linear position

Life of this patent

Abstract

Claims11