US 6,470,713 B1Granted

Method and apparatus for monitoring run/stop conditions of a yarn

AssigneeIropa AG

InventorStefano Lamprillo

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Abstract

A method and apparatus for monitoring run/stop conditions of a yarn, particularly in a knitting or warping machine utilizing a yarn feeler. The yarn feeler includes an electronic, yarn actuated transducer operating with variable gain amplification of run input signals which are further processed to final output signals representing the run/stop conditions. The amplification gain for the run input signal is automatically electronically controlled with a time delay and is adjusted towards a floating minimum which is just sufficient to derive stable final output signals. The, reaction time delay allows compensation for naturally occurring parametric fluctuations of the run input signal, while a sudden drop of the run input signal due to yarn breakage is processed to a final output stop signal.

Claims11

Dependent claims

A method for monitoring run/stop conditions of a yarn in a knitting or warping machine, the yarn traveling with a yarn speed profile varying between minimum and maximum speeds, said method comprising:

providing an electronic yarn feeler including a yarn actuated transducer in contact with the yarn so as to generate a run input signal representing a yarn speed profile of the yarn;
operating the transducer with variable gain amplification of the run input signal;
starting from a predetermined minimum yarn speed-related maximum, permanently and automatically electronically controlling, with a constant reaction time delay, the amplification gain for the run input signal so as to be inversely proportional to the yarn speed profile and adjusting the amplification gain towards a floating minimum just sufficient to provide a stable final output signal;
compensating for natural parametric fluctuations of the run input signal with the reaction time delay while processing a sudden drop of the run input signal due to yarn breakage to a final output stop signal;
and
constantly evaluating the momentary final output signal in view of a simultaneously present sync-signal associated with expected run/stop conditions of the yarn and indicating when the yarn should run and when the yarn should not run.

3 more elements

A yarn feeler for monitoring run/stop conditions of a yarn in a knitting or warping machine, the yarn traveling with a yarn speed profile varying between minimum and maximum speeds, said yarn feeler comprising:

a piezo-electric or electrostatic transducer for generating a run input signal upon contact actuation with the traveling yarn which is based on the speed and/or tension of the yarn;
an amplifier with variable amplification gain connected to said transducer for amplifying said run input signal into an amplified run output signal;
a detector/comparator for comparing said amplified run output signal with a detection threshold to generate a detected run signal;
an output filter connected to said detector/comparator for filtering said detected run signal with a time delay in order to output final output signals representing the run/stop conditions;
and
an amplification gain control circuit connected to said amplifier and to an output of said detector/comparator for generating an amplification gain control signal for adjusting the amplification gain towards a floating minimum on the basis of said detected run signal such that said output filter generates final output signals within specified limits, said amplification gain control circuit varying said amplification gain with a constant reaction time delay which is shorter than a time delay of said output filter.

3 more elements

Dependencies are inferred from the claim text.