Research And Design Of Voice Diaphragm Concentricity Measure System Based On Machine Vision

A loud speaker is a device which can convert electrical signal to voice signal and whose trend of development will be a smaller size and a better timbre. Small speakers have been widely used in consumable electronic products, communications, computers, automotive electronics and other fields. The quality of timbre basically depends on the performance index of the loud speaker, and the concentricity of the voice diaphragm is an important factor which impacts the performance index of the loud speaker.The research object of this paper is the minitype voice diaphragm, which is composed of diaphragm and voice coil. Voice diaphragm would be touched if using the traditional manual way of measuring concentricity, which easily made the diaphragm pleated and the voice coil transformed, and it made measuring concentricity more difficult and brought a big error to the measure result. Aimed at the problem, this paper researched and designed the voice diaphragm concentricity measure system based on machine vision. The key of software algorithm of the system was how to extract edges of outer circle and inner circle.The main research content of this paper can be summarized as follow:1,Based on analyzed the principles and characteristics of Roberts,Sobel,Prewitt,Kirsch,Gauss-Laplace and Canny edge detection operators, they were used to detect edge towards the same bitmap of voice diaphragm. Compared the detection results, Canny operator, which has advantages of high SNR, precise position and single-edge detection result, was chosen as the edge detection operator of voice diaphragm concentricity measure system.2,According to the principle and composition of machine vision and the specific requirements of voice diaphragm concentricity measure system, and based on analyzed the features of voice diaphragm , proper camera, lens, lighting manner, light source and background were chosen to form and realize the vision system of the system.3,The softeware for the voice diaphragm concentricity measure system was designed and realized. According to the characteristic that the diaphragm occupied the largest field of view, the outer circle edge was extracted with the ways of threshold segmentation and contour tracing. There were a lot of interferences around the inner circle. Based on analyzed the source of the interferences and their effects on inner circle edge, and according to the outer circle parameters measured, the inner local area was gotten, and then the inner circle adge was extracted with the ways of Canny edge detection and improved Hough transform. Using Least Square subpixel position algorithm to fit outer circle and inner circle ,the error was reduced ,the measure accuracy was increased. A lot of voice diaphragm were measured with the system。...