The apparatus and methods disclosed herein are directed to detecting the presence of a whipping tail when using a fiber winding system to wind a fiber onto a rotating spool. The fiber is guided onto the rotating spool through a containment region between the spool and a whip shield to create the wound fiber. The whipping tail outwardly extends from the wound fiber and periodically or quasi-periodically passes through a light beam to create a series intensity dips in the light beam, thereby forming a modulated light beam. The modulated light beam is converted into a digital electrical signal made up of electrical pulses having a timing defined by the intensity dips. The measured timing of the electrical pulses is compared to an estimated timing based on the rotating spool to ascertain the presence of a whipping tail.

A method is provided for contactless optical detection of yarn at a workstation of a textile machine in which the yarn moves in a sensing slot between a source of radiation and an optical sensor having at least one row of radiation sensitive elements, whereby shading of the individual radiation sensitive elements by yarn moving through the sensing slot is monitored and a state of the yarn is evaluated on a basis of the monitoring. The method monitors and evaluates a position of the yarn in the sensing slot or a time course of the position of the yarn in the sensing slot. A change is detected in the position or in the time course of the position of the yarn in the sensing slot corresponding to a yarn break before an end of the yarn break passes through the sensing slot. When the yarn break is sensed, a stop signal is generated for the workstation.

A method is provided for contactless optical detection of yarn at a workstation of a textile machine. The yarn moves in a sensing slot between a radiation source and an optical sensor having at least one row of radiation sensitive elements. Shading of the individual radiation sensitive elements by yarn moving through the slot is monitored and a state of the yarn is evaluated based on the monitoring, which includes monitoring and evaluating a position of the yarn in the sensing slot or a time course of the position of the yarn in the sensing slot. A change is detected in the position or in the time course corresponding to a yarn break before an end of the yarn break passes through the sensing slot. When the yarn break is sensed, a stop signal is generated for the workstation.

A device and a method for detecting a distance from a balloon to an ingot tank is provided. The device comprises a set of photoelectric transmitting tube and photoelectric receiving tube which are arranged in a height range of a balloon, Wherein a light beam between the photoelectric transmitting tube and the photoelectric receiving tube is arranged to be tangent to an appropriate balloon, and is used for detecting whether the balloon is located at an appropriate position according to a number of pulses received by the photoelectric receiving tube in one period of rotation of the balloon.

A device and a method for detecting a distance from a balloon to an ingot tank is provided. The device comprises a set of photoelectric transmitting tube and photoelectric receiving tube which are arranged in a height range of a balloon, Wherein a light beam between the photoelectric transmitting tube and the photoelectric receiving tube is arranged to be tangent to an appropriate balloon, and is used for detecting whether the balloon is located at an appropriate position according to a number of pulses received by the photoelectric receiving tube in one period of rotation of the balloon.