Application of on-line yarn evenness measurement through CCD image sensors

This paper introduces the method of on-line measurement of the yarn evenness using double CCD image sensors. The double sensors are mounted on a movable bracket of the small car. The obtained yarn coefficients of variation in the diameter through computer and digital image processing techniques are compared with those of using off-line USTERII evenness tester. Meanwhile, the CCD sensors, avoiding affection of the incident light intensity, overcome the shortcomings of the conventional photoelectric sensors. Combined with modern control theory and textile principal in technique, intelligent algorithm is added to collect and process real-time data of the on-line measuring device. The results show that the average error accuracy is about 4.5%. In addition, it is also found that the achieved data from the on-line device are coherent and correlative with USTER statistical bulletin 2001. The bad test results indicate that there are the thicker and thinner sections in yarn. On the contrary, the good results are expected and consistent with practice. The system, avoiding environmental temperature and humidity, has quick response, flexible and portable installation, simple use, friendly interface.