Abstract Recently, digital transformation is in progress in various manufacturing fields, and the introduction of big data and artificial intelligence technologies is also in progress in contact manufacturing companies. Accurate detection of defects occurring in the color contact lens manufacturing process using artificial intelligence technology is emerging.In this paper, we present a CNN method with a double structure that efficiently finds the color printing pattern, which is essential to detect contact lens defects.In order to apply the proposed technique, a learning model was created to detect the print pattern area using 50,000 image data, and the test result for 1,000 images, 0.05 MAE(Mean Absolute Error) was obtained using this learning model.