Abstract: An apparatus for monitoring a moving filamentary product having a device for monitoring the centering of the filamentary product relative to the coating, and a device for monitoring the quality of the coating. The centering monitoring device includes two light sources positioned at 90.degree. to each other in a plane perpendicular to the filamentary product. The coating quality monitoring device includes an optical receiver disposed between the two light sources in the same plane, and at 45.degree. to each of them, to receive the light beams reflected by the coating.

Abstract: The present invention relates to a method of detecting whether at least one die is centered about a thread held taught between two fixed points separated by a distance L, wherein:the thread is excited into vibration;its frequency F of vibration is measured;the corresponding length 1 of vibrating chord between one of said fixed points referred to as a "reference" fixed point and another point referred to as a "contact" point is deduced therefrom; andlength l is compared with length L and with the length of the segment of thread between said reference fixed point and said die, so as to deduce therefrom:either that the thread is touching said die, if length l corresponds to the length of the segment, said contact point then being situated at said die;or else that the thread is not touching said die, if length l is equal to the length L between said two fixed points, in which case said die is properly centered, said contact point then coinciding with the other one of said fixed points.

Abstract: This invention concerns an apparatus for checking the thickness and uniformity of a coating made of conducting material deposited on an elongated insulating body, this apparatus comprising:a sensor sensitive to the presence of the elongated body and forming part of an electrical circuit powered by a power supply voltage (24),measurement instruments (25) to measure an electrical quantity that is a function of the thickness of the conducting coating, at the output of the circuitequipment for processing the electrical quantity to deduce the thickness of the conducting coating,wherein the sensor consists of a condenser (10) containing two plates separated from each other by an air gap containing a dielectric material, this condenser being adapted to enable the elongated body to pass through the air gap.

Abstract: Apparatus for detecting irregularities in the diameter of a filament has a small light source placed at the focus of an objective lens system. A horizontal slot constitutes a diaphragm for the objective lens system. A first optical system forms an image of the slot in a plane in which the filament runs past. Detectors detect the beam intercepted by the filament. An optical splitting system (P1) is interposed in the path of the beam (A), downstream of the slot (3) and upstream of the filament (5). The system is designed to form two sharp images (3', 3") of the slot (3) in a plane (4). The detectors are two oppositely-connected detectors (D1, D2) each receiving a respective beam (C, C') intercepted by the filament (5).

Abstract: A device for separating two light signals having different wavelengths transmitted in one and the same optical fiber, comprising an optical fiber terminating in two branched-off portions of fiber having in one case an extension of predetermined length, two photodetectors placed respectively at the output of said extension and of the other branched-off portion of fiber, delay means connected to the output of one of the photodetectors, differentiating means for receiving the signals generated by the delay means and the signals detected by the other photodetector, and an electronic processing circuit connected to the output of the differentiator.