Optics: measuring and testing – By monitoring of webs or thread – For flaws or imperfections
Reexamination Certificate
1998-12-31
2001-06-05
Font, Frank G. (Department: 2877)
Optics: measuring and testing
By monitoring of webs or thread
For flaws or imperfections
C356S429000, C356S238100, C356S238300
Reexamination Certificate
active
06243166
ABSTRACT:
The invention relates to a method and a device for detecting impurities in a loosened fiber stream of mainly textile fibers, wherein the fiber stream and at least one reference quantity are artificially visually sensed.
BACKGROUND OF THE INVENTION
From DE-A-4340165 and DE-A-4340173 such methods are known, by means of which, for example, cotton or wool in the form of flocks polluted to a greater or lesser extent with impurities may be freed of said impurities. With said methods it is possible to distinguish between external impurities, which relate to different material, and internal impurities, which relate to the same material but in a different state or a different color. Internal impurities are, for example, cotton or woollen fibers which are partially rotten, agglutinated or contaminated. External impurities are stones, soil, glass, stalk residues, leaves, packaging material, hair, feathers etc. Whereas crude impurities are removed in the known spinning preparation devices, impurities which are more difficult to separate are, according to the known methods, to be detected and removed from the stream of loose material. To said end, the fibers or flocks are conveyed continuously past color sensors which are to detect impurities. Material containing constituents, to which the color sensors have responded, is then removed.
A perceived drawback of such known methods is that many impurities are not detected thereby. one reason is, for example, that impurities, in order to be detected, have to vary in color to a relatively great extent from the textile fibers or the background, which is not always the case. Such known methods do not operate very selectively.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method and apparatus which allow impurities, which are difficult to separate, to be detected in the fiber stream with greater efficiency.
The object is achieved in that the fiber stream is artificially visually sensed together with a reference quantity, which is adapted at least at intervals or from time to time. This may be effected on the one hand in that the fiber stream, which is to be opened into flocks or into individual fibers, is to be sensed against a background, which is likewise formed by the fiber stream and acts as a reference quantity. On the other hand, the reference quantity may be formed, for example, also by a background which is periodically or continuously adapted to the material to be measured. A possible construction comprises, for example, a channel for a loosened fiber stream and a channel, arranged parallel thereto, for a retained fiber stream. The channel for the loosened fiber stream is to be permeable to light and the channel for the retained fiber stream is to be permeable to exactly the same light at one side. The loosened fiber stream is then sensed or viewed against the background of the retained part of the same stream or of a further fiber stream.
The advantages achieved by the invention are in particular that the comparison process or processes, which precede a decision about the absence or presence of impurities, automatically adapt continuously to the true conditions of the fibers carried along in the fiber stream. The adaptability is to be regarded as stable and robust so long as the precondition is met that, from a statistical viewpoint, impurities are rare in comparison to good fiber material. The same advantages are achieved when a fiber stream, which has already been cleaned and freed of impurities, is used as a reference quantity.
REFERENCES:
patent: 5544090 (1996-08-01), Shofner et al.
patent: 44 15 907 (1995-11-01), None
patent: 0 233 446 (1987-05-01), None
patent: 0 226 430 (1987-06-01), None
Burns Doane Swecker & Mathis L.L.P.
Font Frank G.
Punnoose Roy M.
Zellweger Luwa AG
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