Measuring and testing – Instrument proving or calibrating – Volume of flow – speed of flow – volume rate of flow – or mass...
Patent
1986-11-07
1988-11-01
Noland, Tom
Measuring and testing
Instrument proving or calibrating
Volume of flow, speed of flow, volume rate of flow, or mass...
73774, 73800, 250231P, 250227, 356 32, 364508, 177DIG6, G01L 124, G01L 2500, G01G 312, G01G 900
Patent
active
047810564
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical device for strain detection, to a method for the measurement of strain by means of this device, and to their application to scales.
2. Description of Related Art
At the present time, optical devices for strain detection utilizing the deformation of a light guide of the optical fiber type permit the performance of a measurement of the strain applied to a fiber by attenuation of the luminous intensity transmitted on account of the modification of the conditions of propagation of the light in the fiber due to this deformation. Devices of the strain gauge type utilizing the abovementioned property of an optical fiber have been described, in particular, in U.S. Pat. No. 4,163,397 or in European patent application No. 0,082,820. The devices such as those described in the abovementioned documents require the implementation of an additional mechanical structure mounted, for example, at the periphery of the fiber, in order to permit the application of strains and of deformations of a periodic nature over the length of the fiber, the measurement of the total strain applied to the fiber being directly related to the attenuation of the intensity of the light transmitted by the fiber subjected to deformation. Even though this type of device effectively permits a measurement of the load or strain exerted on the fiber, it does not however sanction the simple utilization of a device capable of effecting a weight measurement under the required customary operating conditions of precision, of reliability and of accuracy required for this type of measurement apparatus, or even of a device capable of permitting a two-dimensional reading of the strains or loads exerted on a surface, i.e. a reading of a pressure map.
SUMMARY OF THE INVENTION
The object of the present invention is to utilize an optical device for strain detection which is capable of permitting the measurement of a load or of a mass under the customary conditions required for the weighing operation.
Another object of the present invention is the utilization of an optical device permitting the effecting of a reading of a pressure map over a specified test area or surface.
Another object of the present invention is the utilization of a method for measurement of load or for the recording of a pressure map over a specified test area or surface by means of the device of the invention.
The optical device for strain detection according to the invention comprises at least one optical fiber disposed in such a manner as to form a network. Means for emitting light which are disposed at one end, referred to as the entrance end, of the fiber or fibers and means for receiving light which are disposed at the other end, referred to as the exit end, of the fiber or fibers permit the supply of information relating to the luminous intensity transmitted by the fiber or fibers of the network and a corresponding measurement of the strain.
The process for determining the strains applied at a plurality of points of a test area by means of the device of the invention consists in disposing the network constituted by a plurality of fibers of the device of the invention on the test area. A zero condition of the system for each point i, j of intersection of the fibers is recorded in a memory in the absence of any test load applied to the test area and the network. The test load being applied to the network and the test area, the values of relative strain Fi, Rj which are supplied by the detector associated with each optical fiber of order i, j in a first and a second direction are memorized. The relative strain Pij applied at each point, having coordinates i, j, of intersection of the fibers of order i and of order j of the first and of the second direction of the network is determined by means of a linear combination of the type ##EQU1## where, m and n being the number of fibers,
The invention is employed in weighing apparatuses, apparatuses for the measurement of loads applied to skew surfa
REFERENCES:
patent: 4163397 (1979-08-01), Harmer
patent: 4270050 (1981-05-01), Brogordh
patent: 4295738 (1981-10-01), Meltz et al.
patent: 4321831 (1982-03-01), Tomlinson et al.
patent: 4477725 (1984-10-01), Asawa et al.
patent: 4560016 (1985-12-01), Ibanez et al.
patent: 4603252 (1986-07-01), Malek et al.
Patents Abstracts of Japan; vol. 1, No. 142, p. 205 (1282), Jun. 22, 1983.
Bocquet Jean-Claude
Noel Jacques
Noland Tom
Sopha Praxis
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