Study On Photoelectric Method Of Yarn Defect Online Detection Technology

In the textile industry,there can be defects on the yarn’s surface which is caused by the conditions including the raw materials,equipment,production environment,etc,during the assembly line production.The yarn’s defects mainly refer to the sudden change of yarn’s diameter and the dirty spot on the surface.Yarn’s quality can be largely compromised be these kinds of defects.In order to better control the quality of yarn during the production,we try to use photoelectric method and design a new-type device to measure the defects on the yarn’s surface.Firstly,by changing the light source’s incidence angle and the focal position of lens and sensor,a signal collection method is putted forward to gurantee that the sensor can work with the largest signal-to-noise ratio which is responsible for increasing the amplitude of the sensor’s output signal.Integration design of lens and sensors is also made.Secondly,we design a signal processing circuit to meet the FGPA chip’s using condition about the signal input’s amplitude.Initial signal can be anplified,filtered after through the circuit.Also the signal’s amplitude is larged by the circuit to increase the signal-to noise ratio.Then,the functional relationship between the size of defects and processed signal is deduced by means of the analyze of defects’ size and the corresponding signal’s character.To realize the recognition of defects,using FGPA chip to design the time logic circuit and the comparative logic circuit to identify the pulse width and the peak of the signal respectively.Finally,based on NiossⅡ,we make the calibration of the signal’s pulse width and peak according to the function.,storage and display the eigenvalue.and conduct the analog signal tests.The experimental results show that the photoelectric yarn’s defects detection system can extract the characteristic signal variation on the yarn surface during the movement,and effectively suppress the external noise in the laboratory environment.When the yarn moves at 30m/min,the detection system can effectively detect yarn defects greater than 50um.