Automatic recognition system for color drawings of printed circuit board

Abstract

AbstractThis paper describes the automatic input system for color drawing, which reads the printed circuit board pattern written with different colors for lands, vias and signal line patterns, and recognizes the elements to construct the input data for CAD. The object is a color drawing based on the traditional expression, which is drawn rather fairly in detail using color pencils, for use in the design of the printed circuit board pattern. In the processing of the color drawing, the discrimination of the color implies the discrimination of the elements in the drawing. Consequently, an exact color separation method for the image data is proposed. By the proposed processing, the color separation is realized easily in spite of the color variation, by constructing interactively the color separation map using a small computer. As the recognition of the figure element for each color, a correction method for the figure is proposed, which may contain modifications such as the noise of color pencil or the line disconnection due to overlapping of different colors.In the proposed method, the properties inherent to the printed circuit board pattern are utilized as the knowledge, and an intelligent figure processing is executed such as connection of vectors or shaping. As a result of a test using the implementation design drawing, an exact color separation was realized for the drawings of the layers drawn using four colors: red, blue, orange and green. The recognition rate for the figure is above 99.7 percent. The processing time for A1 drawing was approximately 12 min using a large‐scale general‐purpose computer. These figures are sufficient for application.