METHOD AND ARRANGEMENT FOR OPTICAL CONTROL OF THE NEEDLES OF KNITTING MACHINES

For controlling the quality of the needles of a knitting machine a test image of each needle is acquired with the aid of an image sensor when the needle is moved out of its rest position for forming a stitch. The analog image signals obtained on reading out the image sensor are converted to digital pixel signals, and the digital pixel signals of the test image or of individual test zones of the test image are processed for recovering information on the state of the particular needle being imaged. By using a coarse resolution image sensor it is possible to detect major faults during the normal operation of the knitting machine at full working speed. Needles exhibiting wear and minor faults can be detected by using a high resolution image sensor during special inspection times in which the knitting machine is operated at reduced speed.