Optics: measuring and testing – Velocity or velocity/height measuring – With light detector
Patent
1989-01-16
1991-11-12
Hellner, Mark
Optics: measuring and testing
Velocity or velocity/height measuring
With light detector
356429, G01S 1758
Patent
active
050642804
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a method of measuring the velocity and/or length of endless webs of textile material and an apparatus for carrying out this method.
Normally, in the textile industry the velocities or lengths of conveyed endless webs are measured according to the mechanic rolling method. According to this method a measuring wheel which is connected to a speedometer is brought into contact with the respective web which has to be measured. This web is for instance a two-dimensional structure or a yarn. Furthermore, it is known to connect the measuring wheel to a deflection roller at which the endless web is deflected in order to determine in such a manner the velocity of the transported web which is in contact with the deflection roller by measuring the velocity or the number of revolutions of the deflection roller.
However, the above-described mechanic rolling method can cause a number of problems. So, for instance, with sensitive webs the danger exists that the surface of the web is damaged by the positioning of the measuring wheel which, for instance, results in a surface roughening linearly extending in the running direction of the web or in displaced spots. The application of the measuring wheel can result in a deformation in this area especially with elastic articles, as for instance knitted fabrics, which brings along corresponding faulty measurements of the length of the web. The above-described second method according to which the web velocity or the web length is derived from the velocity of the deflection roller or its number of revolutions brings along the danger of faulty measurements, too. So, for instance, by this slippage effects between the web and the deflection roller which substantially influence the results of the measurements cannot be excluded. This is especially then the case if wet webs are conveyed over such a deflection roller or if the web makes necessary an especially smooth and polished deflection roller due to its sensitivity with regard to mechanical stresses.
It is the object of the invention to provide a method and an apparatus of the cited kind with which an especially exact measurement of the velocity and/or the length of running webs is possible.
This object is achieved by a method having the characterizing features of the claims and by an apparatus having the characterizing features of the claims.
The inventive method is based on the fundamental idea to not carry out the measurement of the velocity or of the length of the running web by direct contact of a measuring wheel with the web or by deflecting the web over a deflection roller the velocity or number of revolutions of which is determined, as this is the case with the above-cited prior art. The inventive method rather proposes a direct and contact-free measurement of the velocity or of the length of the web. According to this method, a light beam is directed to the running web wherein a portion of the light beam has been deflected before and has been supplied to evaluation means. Surpisingly, it could be observed that the beam impinging on the surface of the textile web is reflected by the surface such that a reflection area results which is still relatively narrow. This is surprising since one would have expected that the web would reflect in all directions, scatter and/or adsorb the directed light beam on account of the plurality of reflection areas of such a surface and of the adsorption characteristics of the web so that a reflection area would result which cannot be exactly evaluated. As already stated above, this does not result with the inventive method so that a selected portion of the light beams from the reflection area can be directed through a convex lens and can be superimposed with that portion of the light beam which has been deflected before. By this, various Doppler frequencies, i.e. interferences, result in response to the respective velocity of the web which have the result of intensity variations of the light beam. Evaluation means which receive the superimposed light beams determin
REFERENCES:
patent: 3517998 (1970-06-01), Pryor
patent: 4126392 (1978-11-01), House
patent: 4181432 (1980-01-01), Flower
patent: 4334779 (1982-06-01), Domey et al.
patent: 4679932 (1987-07-01), Morishita et al.
patent: 4696568 (1987-09-01), Weistra
"A Laser Doppler Velocimeter for Surface Velocity Measurement", R. Saarimaa, J. Phys. E: Sci. Instrum., vol. 12, 1979.
Melliand Textilberichte, Band 51, No. 8, Aug. 1970, "Beruhrungslose Geschwindigkeits-und Wegmessung durch Laser-Doppler-System (LADAR)", p. 978.
P. A. Davies et al., "Reflection from a Transversely Moving Mirror-Experimental Details", Jour. of Physics E, Scient. Instr., pp. 245-248.
Ringens Werner
Schmitz Franz J.
Schollmeyer Eckhard
Deutsches Texilforschungs-zentrum Nord West e.v.
Hellner Mark
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