Patent EP-0979795-B1 (EP)
Inventor: HERMANNS FERDINAND-JOSEF DR-IN
IPC: B07C5/10
Filed: 1999-06-30
Granted: 2003-02-19
Abstract: Detect waste yarn material on the sleeve (6) of a spinning cop, it is illuminated to give reflected light as a surface image. The image data are converted into digital image data (90) to be passed through an edge filter. The edges in the image matrix from the digital image data (90), formed by brightness transits, determine the presence of waste yarn present at the cop sleeve (6). At least the section of the sleeve (6) where yarn can be present is illuminated by a stationary lamp, using diffused light, while the sleeve (6) is being moved. When yarn is detected at the cop sleeve (6), a discrimination is made between a length of yarn present which can be used, or whether the detected yarn is to be discarded. The evaluation is effected by a computer (10) which processes the image data (90). Before the image data (90) are passed through the edge filter stage, the contrast is increased, and the image matrix is quartered into pixels. The quartered image matrix is added to the original image matrix. The edge filter uses a Sobel algorithm followed by conversion into a binary structure, for the edges in the digital image data (90) to be processed. The edges, developed by the edge filter stage, are thinned to erode the binary image matrix, to give a difference between the eroded image matrix and the edge-filtered binary image matrix. After the edge filter stage, the edges are traced at the image matrix, to give the contours of registered objects, using a Freeman chain code. The character of the marked contours at the cop sleeve (6) determines irregularities at the sleeve winding surface. An Independent claim is included for an apparatus with a camera system (8,9) to register the reflected light from the cop sleeve (6). It gives digital image data (90) for computer (10) image processing to be passed through an edge filter to show the transits in brightness at the edges and determine whether there is still yarn wound on the sleeve (6). Preferred Features: The lamp (7) is stationary, and aligned to illuminate at least part of the sleeves (6) where there could be wound yarn present. The lamp (7) has a number of light emitting diodes (LED), which are ultra-bight and in different colors in a matrix mix, with at least one white lamp. A diffuser (18) is between the lamp (7) and the sleeves (6) under scrutiny, to control the illuminating light at the sleeves. The lamps (7) are to the side to give a total reflection of the emitted light for the camera system (8,9). The camera system has a video color or black/white camera (8), with a following image converter (9) to provide digital image data (90) with different gray stages. The camera (8) is turned by 90 degrees round its optical axis, to take the reflected light. Or the camera (8) is a digital camera, to transmit digital image data (90) to the computer (10). The camera has an optical distortion system, to match the length:width ratio of the cop sleeve (6) to the camera window, using a concave mirror or a cylinder lens. The computer (10) can discriminate between usable and unusable yarn wound on the sleeve (6), where the image data (90) are stored by vectors.