Real-time Measurement System Of Rough Surface With Subpixel Accuracy

1. INTRODUCTION TO THE PAPERThe technique of paste coating on battery electrodes is key technique in the development and produce of the li-ion batterys used in the mobile telephone. Thickness and thickness uniformity of coating layer on battery electrodes are decisive factors to the quality of the batterys. The measurement of thickness and thickness uniformity of coating layer on battery electrodes is an important working procedure in the produce of the li-ion batterys used in the mobile telephone and the important means to guarantee the quality of products and improve efficiency. The superficial grain noise of coating layer on battery electrodes is bad. How to accomplish the on-line real time measurement of thickness and thickness uniformity of coating layer on battery electrodes which grain noise granularity is more than the measurement accuracy is main content of the research. 2． DIFFICULTY TO THE PAPERThe mission of the subject is to implement the on-line real time measurement of thickness and thickness uniformity of coating layer on battery electrodes with great grain noises. The demand of measurement accuracy is 5 microns. The difficulties of the research include the accomplishment of measurement accuracy and on-line real time measurement. Sometimes two respects are contradictory. It is difficult to accomplish on-line real time measurement, because the image processing algorithm is complex in order to attain the high measurement accuracy. We need to gurrantee the high measurement accuracy and accomplish on-line real time measurement. There are some difficulties in the reseach.1. The quality of the surface measured is bad, and the granularity of superficial grain is more than ten microns. The image speckle noise brought by the superficial grain is bad. It is difficult to accomplish on-line real time measurement and attain the high measurement accuracy.2. It is difficult to accomplish real time image dada acquisition and processing system, and attain the high measurement accuracy. In order to attain the high measurement accuracy the image processing algorithm is complex. It is difficult to accomplish real time image processing algorithm.3. The aim of measurement system in the paper is to accomplish high accuracy measurement of rough surface. It is difficult to evaluate the measurement result and optimize the measurement system parameter by means of the experiments.3． THE DESIGN TO MEASUREMENT SYSTEMThe mission of the subject is to implement the on-line real time measurement of thickness and thickness uniformity of rough surface. Measuremnet system function structure is shown by figure (1). The measurement system consists in laser trianglulation measurement unit, real time image acquisition and processing unit and measurement result display unit.The laser trianglulation measurement unit consists in laser and optics enlargement unit.The real time image acquisition and processing unit consists in CCD, video signal analog-digital convert unit, image processing hardware unit and harmonization logic unit.Figure(1): Measuremnet system function structure 4． RESEARCH ON MEASUREMENT PRINCIPLEOn the basis of the actual situation of the subject and mesuremnet demand, the measurement method of thickness and thickness uniformity of coating layer on battery electrodes using line edge structured laser trianglulation measurement equipment is presented in the paper. The measurement accuracy requireed is 5 microns. Results of experiments show that the measurement system attained subpixel measurement. A detailed analysis is made on quality of the surface and a research is made on error mechanism result from the measurement using the center of gravity method. We find that the measurement method of thickness and thickness uniformity of rough surface using the center of gravity is limited and unfit for the high precision measurement of rough surface. The center of gravity method is unfit for the measurement of thickness uniformity of rough surface. The line ed...