Structural monitoring apparatus

• US 6,703,600 B1
• Filed: 10/22/2002
• Issued: 03/09/2004
• Est. Priority Date: 10/30/1998
• Status: Expired due to Fees

• Current Assignee: EFS International SA
• Original Assignee: Malcolm H. Hodge
• Inventors: Hodge, Malcolm H.
• Primary Examiner(s): PYO, KEVIN K
• Application Number:
  US10/277,269
• Time in Patent Office: 504 Days
• Field of Search: 250/231.13, 250/231.14, 250/231.16, 250/231.18, 250/237.R, 250/237.G, 250/227.11, 250/227.12, 250/227.26, 250/227.28, 250/221, 738/00, 385/12, 385/13, 356/614, 356/616, 356/617, 356/619, 356/622
• US Class Current: 250/227.11
• CPC Class Codes: G01D 5/34 the beams of light being detected by photocells

Abstract

An optical encoder for detecting movement of a first structural element relative to a second structural element. The encoder includes a transmitter portion connected to the first structural element and having first and second optical fibers arranged side by side. Each of the first and second optical fibers has an end surface which lies in a first plane. The encoder also includes a reflector portion connected to the second structural element. The reflector portion has a plurality of spaced reflective surfaces which face the end surfaces and lie in a second plane spaced from and parallel to the first plane so that pulses of light from an interrogation source can be transmitted along one of the first and second optical fibers toward the reflective surfaces and pulses of light reflected from the reflective surfaces can be transmitted along the other of the first and second optical fibers toward the interrogation source.

Claims

1. A monitoring system for detecting movement of a first part of a structure relative to a second part of said structure, said monitoring system comprising:

(a) an interrogation source comprising;

(1) a light emitting element for emitting pulses of light;

(2) a first light detecting element; and

(3) a second light detecting element; and

(b) an optical encoder comprising;

(1) a transmiter portion adapted to be connected to the first part of said structure, said transmitter portion having a first optical fiber connected to said light emitting element, a second optical fiber connected to said first light detecting element and a third optical fiber connected to said second light detecting element, said first, second and third optical fibers being located in a row longitudinally of a first longitudinal axis with said first optical fiber being located between said second and third optical fibers, each of said optical fibers having an end surface which lies in a first plane; and

(2) a reflector portion adapted to be connected to the second part of said structure, said reflector portion comprising a plurality of photo reflective surfaces facing said end surfaces and being spaced longitudinally of said first longitudinal axis,said photo reflective surfaces lying in a second plane spaced from said first plane so that pulses of light from said first light emitting element is transmitted along said first and second optical fibers toward said photo reflective surfaces and said pulses of light reflected from said photo reflective surfaces to the end surface of said second optical fibers is transmitted along said second optical fiber toward said first light detecting element, and said pulses of light reflected from said photo reflective surfaces to the end surface of said third optical fiber toward said second light detecting element, said reflector portion being adapted to be connected to a second part of said structure and movable relative to said transmitter portion along a second longitudinally axis which is at an acute angle to said second plane, so that movement of said reflector portion relative to said transmitter portion along said second longitudinal axis in one direction increases the distance between said end surfaces and said second plane and movement of said reflector portion relative to said transmitter portion along said second longitudinal axis in a direction opposite to said one direction decreases the distance between said end surfaces and said second plane so that the amount of and direction of movement of said second part relative to said first can be determined through the use of quadrature.

2. The monitoring system as recited in claim 1, wherein each of said first and second light emitting elements is a light emitting diode.

3. The monitoring system as recited in claim 1, wherein the width of each of said photo reflective surfaces along said first longitudinal axis which is substantially half that of the distance between adjacent ones of said photo reflective surfaces.

4. The monitoring system as recited in claim 1, wherein said second plane is at an acute angle to said first plane and said second longitudinal axis is parallel to said first plane.

5. The monitoring system as recited in claim 1, wherein said acute angle is not greater than 5 degrees.

6. The monitoring system for a structure as recited in claim 1, wherein said transmitter portion comprises a housing having a chamber, a first end opening to the chamber at one end of the housing, a second end opening to the chamber at the opposite end of the housing, a side opening to the chamber and a ferrule located in said side opening and containing said optical fibers, and wherein said reflector portion comprises a body located within said chamber and a shaft fixed to said body within said chamber and extending through said first and second openings, said body having said photo reflective surfaces.

7. The monitoring system as recited in claim 1, wherein said transmitter portion comprises a housing having a chamber, a first end opening to the chamber at one end of the housing, a second end opening to the chamber at the opposite end of the housing, a side opening to the chamber and a ferrule located in said side opening and containing said optical fibers, and wherein said reflector portion comprises a shaft within said chamber and extending through said first and second end openings, and a wedged shaped encoder strip containing said photo reflective surfaces which face said side opening, said shaft having a central longitudinal axis which is coaxial with said second longitudinal axis.